Hey All,
I am new here and this is my first post (Sorry it will be long). I have done a bunch of reading over the last few days on this site and am impressed by the helpfulness of people here.

I am trying to get my system set up well but will give a bit of background.

My wife and I purchased our home 3 years ago now. The pond of the property is about a 1/4 acre maybe a tad more. Oval in shape (Approx 60'x180'). It's about 7' deep on one end and about 12' on the other.

There was an aeration system when we got here. The compressor is at the house under an roofed deck with about a 300' run to the pond with 1.25" black poly pipe run underground to the pond running to one stone type stick diffuser in the deepest part of the pond.

The pump was old and loud so we didn't run it this past year and had a significant amount of weed growth over last summer and a significant fish kill this winter.

I just purchased a rebuilt compressor from a local source (Thomas 2650) and a cheap ring diffuser just to get me going again. I split the line down at the pond so I could run the old and new diffuser on both ends of the pond.

Since reading on here I am convinced I need a check valve, pressure gauge, and relief valve. I will also be purchasing a vertex diffuser from ForeverGreen as these seem to be the best. I am hoping I can use my current compressor and somehow put the check valve, pressure gauge, and relief valve on it.

Any suggestion are appreciated on how to go about this. I would like not to have to run another line from the compressor to the pond and am hoping splitting it at the pond is ok.

Currently I size up to the 1.25" about 6' from the compressor and then down to 3/8" split at the pond. At the pond there is 3/8" weighted line running 25' out on the deep side of the pond (12" deep) and about 70' of 3/8" at the split running along the shore to the shallow side and the 25' of weighted out to the 7' depth.

All suggestions are appreciated. And Thanks ahead of time.

At the pond, make a manifold. 1.25" line going in one end, "T" off a couple ball valves, and attach the line from each diffuser to the ball valve. That way you can regulate the amount of air to each diffuser. I'd make sure I had at least one extra "T" so you could bleed off extra air if needed. Put the manifold in a box to protect it from the elements.

Should the check valve, pressure gauge and the relief valve be at the compressor or the at the pond where I make the manifold?

Just thinking, it seems they would all be best at the compressor but if I am wrong it would be easy to put them in a box by the pond.

I should have mentioned that right now I have an inline ball valve in the 3/8" tubing leading to each diffuser. However, I have no idea of what I have for pressure anywhere in my system.

compressor

Scott,

I've done both with no issues.

Thanks for the help so far. I am looking forward to learning and doing this as right as I can with what I have.

What kind of pressure should I be looking for at the compressor? All I know for specs is I believe it is 5.4 cfm open flow 30psi max.

The Thomas 2650 has two 1/4" outputs on it. Right now I have a plug in one. Can I put the pressure gauge on the compressor outlet opposite the output for the airline or should I build a manifold so that the pressure gauge can be on the same outlet as the airline?

Also, any suggestions for a relief valve? Would an adjustable air compressor pressure relief valve work? I have a couple 0-100 psi ones already.

Per Thomas' website for the current 2660 model, they run 4.6cfm at 0 psi down to 3.6cfm at 40 psi which is max continuous pressure rating.

That said, it is a positive displacement pump. It will generate the pressure required to deliver the massflow. Essentially, the line and diffuser losses. It will vary totally with what you hook on.

As max pressure occurs at the pump and that is what you want to protect, regulate there. From the photos, it looks like the two heads are manifolded together across the top of the unit. You could put the gauge on one output port and discharge from the other, pressures should be pretty much the same. At max flow, you would likely get a little more out of it if you discharge from both outlets and manifold together using larger than 1/4" tubing as you'd avoid losses through the manifold between heads and have lower velocity/loss than via single outlet.

Ballpark figure go with .5 psi for every foot of diffuser depth. Also, look at the volume of air that you are pumping vs. length of run for that particular size tubing. Smaller dia has more friction. Like trying to breathe thru a straw vs. a 1 1/4" piece of tubing.

Thanks for the continued responses. Looks like I have some figuring out to do but think I am on the right track.

I will be picking some stuff up to make a manifold and will see what kind of pressure reading I get. I am sure I will have more questions.

Thanks for helping me get this under way.

Any recommendations for a check valve and pressure relief valve? Trying to figure out what will work.

Also, is it possible to aerate too much?

In the water, you preferably want a check valve that does not have a spring. Springs underwater tend to clog, corrode and cause malfunction. Check valves underwater should be cleaned annually for dependable operation. Some commercial diffusers have built in check valves. Do due diligence.

I prefer adjustable pressure relief valve to optimize the pressure relief for the type of compressor and aeration system.

Aerating too much - all depends. Too strong of aeration, as in sewage treatment and turning your pond into a 'blender', keeps fine detritus particles in suspension causing turbid water but relative fast decomposition of organics. If the aeration system is sized 'properly' then operation of 24/7 is suggested mainly to error on the conservative side and cover most all cases. I prefer to slightly over size the system and then run the system on a timer to reduce electrical costs yet maintain adequate oxygen on the bottom. There are many exceptions. Each pond similar to humans is different in age, history, chemistry, and nutrient budgets thus it is hard to promote blanket statements.

Is it better than to have the check valve in the water vs at the compressor? I am planning on buying two vertex diffusers this month which I believe have the check valves in them. Any reason to run one at the pump?
Will a standard, adjustable air compressor pressure relief valve work?

I went from having a clear weed free pond to in the last two summers (record heat and sunny) having weed filled can't to the point it's unfishable.

I believe much of that is my fault as I only ran the aerator on the hottest days and not at all in the winter do to the compressor being noisy.

That said, the water clarity is still very good even with the new compressor running two cheap diffusers at this point. There is good visibility down to around 8ft and then you see decaying weeds.

I am hoping by running the aerator and raking the bottom I can prevent those weeds from turning into muck and prevent some regrowth. There is not much muck currently on the bottom less than 3 inches at this point.

As long as over aerating won't hurt anything thing I would rather have too much than not enough. It only cost me about $12 per month to run the compressor so that is not a concern.

A lot to learn here. Thanks for all the help.

I suppose any standard adjustable pressure relief will work. I only an familiar with the one sold by GAST Mfg with 3/8" threads. From the factory it is set for full relief at 15psi. Maximum setting would be around 25psi. If depth of operation is greater than 30ft then another type pressure relief would be better.

A pond from clear to weedy can be due to several things but it is likely that too little aeration caused the excess 'weedy' condition. Type of weeds is the main factor to consider. Are weeds filamentous algae of rooted vegetation with leaves stems and roots?

Excess weed growth very often results in clear water as you are noting.

I think it's Curly Leaf but not 100% sure. It is that type anyhow.

I just installed a pressure gauge at the compressor and it is reading 3psi. If I stop the flow by pinching off the hose for a second it jumps over 30psi. Not sure how to understand the pressure ratings. The pump is 4.5cfm open flow I believe.

I talked to Ted Lea today and will be ordering a pair of single disc Vertex diffusers. One for each side of the pond.

A positive displacement pump will increase pressure to maintain the volumetric flow if you backpressure it. That isn't great for life to deadhead it. You want to keep it at low pressure.

I sent some questions to the mfgr as I was curious. They responded with some very useful info. I'd be thinking about his advice on moisture control and rebuild intervals.

The piston pump is a good choice for pond aeration. The 2668 is a two
headed pump with an integral manifold that connects the two heads in
parallel. On the attached drawing you'll see there is one inlet connection
(that allows incoming air to enter both heads at the same time, and one
discharge connection. Therefore, we are adding the flow each head
together. You could 'T' into the discharge line for a pressure gauge.

This pump is rated for continuous duty and can run 24/7. Pump life depends
a lot on the operating pressure and pump operating temperature. The higher
the discharge pressure, the more pressure is placed on the piston seal
forcing it against the cylinder and creating more friction. Also, the
higher discharge pressures create higher operating temperatures. The
installation must have as much cooling air as possible - the cooler the
pump runs, the longer the piston cup will last.

The piston cup is the main wear item. It is a Teflon impregnated compound.
I would expect at least a years worth of running continuous in a good
installation, and as much as 3 years in the right conditions. I would plan
on a rebuild once a year, but monitor how the pump does to see if you can
stretch this. One other note of caution - piston pumps do not handle
moisture at all. If any liquid gets into the pump, the piston seal can
wear out in a matter of days. Please make sure to mount the pump so that
the discharge line is piped down so that when/if the pump stops and
condensation occurs due to cooling, it will not flow back into the pump.
You may want to consider a discharge check valve to prevent any backflow.

I would suggest a tube ID of no less than the discharge port size (1/4"),
and certainly stepping up to 3/8" or 1/2" will reduce pressure drop, but
not significantly at this low flow.

Your other choices for pumps would be a rotary vane or a diaphragm pump.
These tend to be more expensive and don't offer any advantage from a life
standpoint. However, the diaphragm pump can handle moisture better than
any of the other two.

Good info, thanks for posting that.

My entire system runs downhill so I guess I am good there. The pump sits in our carport so has good ventilation and stays dry other than humidity. I will probably install a check valve at the pump output to be safe.

Right now both ports are manifolded together as from the factory. One input is open with a muffler and filter. One output is open going from the 1/4" up to 5/8 for 10' then to the 1.25" black poly which runs 300' to the pond.

Off the output I have two 1/2" T's with a pressure gauge on one and a relief valve on the other.

At the pond is probably my weak point as the line downsizes to 3/8". 50' of weighted to one diffuser in 12' of water and 100' to the other in about 7' of water.

I just bought two Vertex diffusers from Ted Lea that came today which will replace the two stone sticks in the pond now so that should increase the efficiency.

Hoping the 3/8" ID line at the pond isn't an issue and I'm not even sure in a .25 acre pond I need two diffusers running 24/7 but that's the plan for now. Hoping over aeration isn't an issue.

Not even sure I am doing any of this right but at least I am learning.

Only running 3 psi nominal kinda indicates most all the air is going through your 7' diffuser and very little to your 12' diffuser, plus your 300' run loss is tenths of a psi (good). To get to your 12' deep diffuser, it would take (62.4 lbs/cu ft * 12 ft / 144 sq in/sq ft)=5.2 psi. Then you have the diffuser loss to add in, so you'd be seeing 6 psi or so. Such a system would take the path of least resistance in the vernacular, and go out the shallow leg. You don't mention valves at your split to regulate flow. May want to add a simple ball valve on each leg and close down the shallow leg a little. Your goal might be to have equal flow thru each leg and that would require an additional pressure drop on the shallow side to equal the added depth on the deep leg.

Nick is right here you should have a ball valve or gang valve to regulate flow if your going to run both of them. Unless your pond is very oddly shaped I would say no you don't need both fusers running in that size pond. The 12 foot one should be fine. Move the other one to about 3 feet and use it in the winter to keep an open hole for air to help your fish get the D.O. they need in the winter. You could still use gang valve to swap over or you could just dissconnect one hose and put the 3 foot hose on in the winter time.

Good Luck,
RC

The pond is a standard oval shape. I do have inline shutoff valves in the lines to each diffuser so I can regulate/shut off flow.

My main reason for running both right now is trying to speed up the decay process of the weeds that grew the last 2 summers. I figured since I already had a fish kill and looks like almost total I wanted to try to get the weeds under control.

My plan for the future is exactly what you mention. Run the diffuser in the 12' section in summer and at about 3' in the winter.

One thing I am still wondering is can you over aerate a pone to the point of damaging it?

I certainly do appreciate all the help.

I am no expert but I have not ever heard of that? A lot of folks run their systems 24/7 once you have saturated your pond with D.O. to the point where it can not hold anymore your basically runnning your system to maintain that level. Once air is established I have never heard of anyone losing fish because of over aeration keep in mind I said I have never heard of it. I am not 100 percent positive. Most of the time the big concern is getting your air started and running up to speed without hurting any fish. Once that is done your good to go from everything I have read. Think about this. I have had a 200 gallon fish tank I had LOTS of air running it it 24/7 and it never hurt those fish.

RC

New development.

I hooked up one of my Vertex diffusers and lowered it on the 7ft side. My psi gauge then went up to 10psi and the relief valve was going off.

I disconnected it and went back to the old stick/stone diffuser and it drops down to 6psi which is still higher than the 3psi it was running before. Not sure what changed.

Any thoughts?

I did add drain the pond down about 3ft due to the fish kill so I can clean up some cattails and added some fluridone and blue uv dye to try to take care of some of the curly pond weed. Can't imagine any of this would cause an issue.

The Vertex diffuser might not need all the air that your compressor is producing. How many cfm are you trying to shove thru the diffuser?

Good point. Not sure how many cfm are going to the diffuser. The compressor is rated at 4.5 open flow. Not sure what that equates at the run I am making.

Is there a way to figure the cfm output at the end of the run?

Thanks

Give Ted Lea a shout. He should know.

Ted Lea will also advise with this. The increased pressure of both the V.diffuser and stone could be due to a kinked air hose or blockage in the hose. You may have kinked the hose under water. Something is causing restriction of air flow, thus increased pressure reading. Take the diffusers off the hose and see if the psi is 0 with hose end out of water. It should be 0 or very close to it. Figure out what is restricting air flow and you will solve your problem. A dual V.diffuser assembly should easily handle 4.5 cfm. Although at 7 ft deep you will probably not be producing 4.5cfm, more closer to 3.8-4cfm. CFM at various depths will depend on type of compressor.

I pulled the Vertex diffusers and went back to the old stone diffusers on both lines and psi is back to normal about 5psi. Unfortunately with the weather I am not sure when I will be able to get the Vertex ones hooked back up to see what is going on.

As long as I know the Vertex diffusers can handle the output of the compressor I have then I will start looking at other potential issues.

Hopefully tomorrow I can experiment some and see what I can figure out.

I am pretty sure the line wasn't kinked. It is all new, self sinking line and was tight when lowered into the water.

Thanks for the info. I'll keep you all informed.

Nate, you have gotten some really good advice. Read it over carefully and all the information is there. I am just going to reiterate a couple things, just in case you did not catch it reading the previous posts.

Your compressor, if in good shape, should output XX amount CFM at a given depth. The deeper the water, the more the back pressure on the compressor, the lower the CFM. As was pointed out, about 6 psi is what your pressure should be at the compressor head to be able to push the air out against the static water pressure at thhe 12' depth plus what resistance is in the line and diffuser. So if the pressure reading is significantly higher than that, something is amiss.

My first suspect is the diffusers might be under sized for the CFM you have, since they were the variable you changed that changed the pressure reading.

A membrane diffuser is sized and has holes to operate correctly at a given CFM flow (actually has a "range" of acceptable operating CFM flows). If there is more air flow (to high CFM) than the holes and size of the diffuser can handle, it will balloon up and force the holes bigger, reducing the output of the compressor at the higher psi while at the same time over flexing the membrane. This will cause the membrane to fail prematurely, like a balloon being over inflated.

IF this is the case (and it might not be, just check the specs on the diffusers for their CFM rating). The output of your compressor at the depth it is running (12') should fall within the range of the sum of all the diffusers added up can handle. If you have more CFM than what the diffusers are rated for, you can either add more diffusers (like a dual, triple or quad diffuser), use a bigger diffuser, or bleed off some air from your compressor so not all the air goes to the diffusers. I personally would want to use all the air you are paying electricity for to compress, even if it meant going to bigger holes and bigger bubbles or a larger or multiple diffuser. But that is just me (and I am not at all an expert).

All of this information was included in the previous posts if you read through them carefully. I have said nothing new, just presented it in maybe a more explanatory way.

This all makes a lot of sense. Thanks for the summary.

The Vertex diffusers are rated at .5cfm to 2cfm. If I was trying to run one of those with my compressor which puts out 4.5cfm that would probably be what caused my pressure at the pump to go up.

I am wondering if I may not need to bleed some air off or at least run both diffusers even though not needed for the size of pond I have.

Any harm in running both? Can you turn the pond over to much? Doesn't seem like it would be an issue.

I am hoping to create some good water for the family to swim in as well as restock with bluegills so my 2 and 4 yr old can have some fun catching fish in the future.

I built a manifold tonight that I can hook up when it's nice again. It will allow me to have both diffusers plus a line to bleed off air if needed.

Thanks again everyone for getting me headed in the right direction.

Sounds like you are on the right track to me. One diffuser = need to bleed some air off. Two diffusers will be about perfect. Remember, your pump will put out somewhat less CFM against a 12' static water pressure (6 psi) than it will open flow. So you might have only 3.5 or 4 cfm at 6 psi.

Like I said before, I'm no expert. I have run pond aeration for a total of two or three weeks last fall as a temporary experiment in preparation for installing a permanent system later this spring (soon I hope). My knowledge is mostly from reading a bunch (here on PBF as well as mfg spcs) last year in preparation for installing a system myself. But I have had many years with pressure and flow rates in hydraulics and air so have what I feel is a very good layman's working knowledge on flows and pressures. I'm also a scuba diver and understand static water pressures at depth. So that is the background I speak from. Definitely not from years of experience with pond aeration systems.

With the above in mind I will give an opinion (that very may well be wrong because of lack of experience, but it is worth every penny you paid for it )

My opinion would be, where you have had a fish kill, you want to clean up some muck, where you are in "remediation" mode, my OPINION would be you could use all the air you could get. You might stir the pond up and make it turbid with old muck. So what? Nutrients stirred up should give you a good algae bloom. It might make your water look "yucky" for a while, but the added disturbance should get you the quickest results of remediation.

After all what does the air do? It moves water. The bubbles don't do much themselves except move water. The bubbles are inducing current to move water. I don't see any way (and I have been wrong before, many times, so it is an opinion, not expert advice) that you could produce too large of current in the water to hurt the current fish population or do any permanent damage. If you don't like the results being obtained, do something different.

If it were me, I'd go for it. Move some water with all the air you got.

^^^ what he said!

NateS - Try this for some troubleshooting your extra psi problem. I am pretty sure the Vertex membrane diffuser was designed to normally handle or operate at 0.5 to 4cfm with peak flow of 6cfm were damage to the diffuser could occur. Ted Lea could confirm this. To test the Vertex diffuser which I assume is a dual head model, connect the diffuser directly to the compressor using a short piece of 5/8"ID hose. The diffuser should be out of the water and near the pump so the only thing receiving air is the diffuser through a short hose. Dual head diffuser will result in each membrane getting less air volume than just one membrane. Turn on the pump and the gauge (30psi model) should read 0 pressure. I just tested a single Non-Vertex 9" membrane connected to the pump with 4.5 cfm and pressure on gauge read 0. This test means there are enough holes and large enough holes in the diffuser to not cause backpressure on the pump. The Vertex diffuser could be causing some sort of back or head pressure.

I'll give that a try. I bought the single disk diffuser pack. It is 2 single disk diffusers without a base. I built the base and plumbed the connection system for it.

According the Vertex sight each diffuser is rated for .5 cfm min to 2cfm max.

I need some nice weather so I can get out and play with this more. I can do the direct hookup though since the compressor is under my carport and out of the weather.

Thanks

Double check with Ted L. I think 2cfm max is for normal operation. I think each of the membranes can withstand more cfm (4-5.5cfm) for short periods similar to what I noted above. Let us know what you find out.

Got a break in the weather and was able to run some tests.

I did as you suggested. I hooked the single disc Vertex diffuser straight to the 5/8" coming out of my compressor. Immediately psi went up to 10. I then tried the other Vertex disc and same thing, 10psi. That is 5/8" line that is running 10', dry.

I then split the line and ran to both diffusers and it dropped to 5psi.

I hooked up a new manifold I made from pvc down by the pond to get rid of the inline valves. Now I have 1.25" going 300ft to the pond downsizing to 3/4" pvc manifold with 3 ball valves so I can have a relief line if needed.

This goes down to 3/8" sinking line to 1 diffuser at about 9' and 1 at about 5' depth. (I lowered the pond about 3' to keep the Fluridone in and give me room with rain to keep the water from reaching the overflow for some time.)

I have the Vertex diffuser in the deep and the old ring diffuser in the shallow.

I am now reading 5.5 psi at the pump with the valve part way shut to the shallow water diffuser.

This seems to indicate to me I need to relieve pressure from just running 1 Vertex.

I am hoping to get in touch with Ted Lea at some point but he has been sick so I don't want to bother him unnecessarily.

Appreciate the help as always and am enjoying learning from everyone's input here.

I want to run both at this point anyhow to speed up the recovery process of my pond.

I could not find a data sheet for a model 2650 but here is a link to a 2660-2680 models and notice in the right hand column the output is 4.4 cfm open flow so should be close performance to your 2650.

On these rocking piston compressors that can handle significant pressures it looks like very little cfm loss at 5 psi. At 10 psi it is only about .2 cfm loss.

Thomas 2660-2680 pump performance PDF

FYI

I would assume the lower the psi the better for the pump although if I am understanding correctly it would be ok for this pump to run at 10psi?

I am going to stick with the 2 diffusers running at this point and in the winter go down to 1 and relieve pressure by running a line directly into the water if needed. I should have no problem keeping it around 5-6psi doing this.

When I get in touch with Ted I will relay any info I get from him about this setup.

Any suggestions on a good air filter setup? I would like to upgrade from the seemingly cheap plastic/foam insert thing that came with it.

I think each Vertex diffuser should take all the air direct from the compressor with 0 back pressure. Ask Ted to connect one of his single diffusers to a 4cfm pump and see what his psi reading is. IMO pressure should be 0 not 10psi. Something seems wrong with this picture IMO. A normal Vertex diffuser should not cause that much back pressure. The only way the psi should be 10 for one diffuser is the holes/slits are smaller than 1 millimeter and too few of them on the membrane.

Snrub thanks a lot for the link to the Thomas compressors. Very helpful.

Just to test things a bit further.

I again connected my single Vertex diffuser (the one not currently in the water) direct to my 5/8" line from my compressor and got about 8 psi. The one in the water consistently give me 10psi in 9' of water and sets my relief valve off.

I then took my extra stone diffuser which is probably 8 years old and hooked direct to the 5/8" line from the compressor and got a 1psi reading.

Looks like I will be making a call to see if Ted or his wife can give me some ideas. I feel bad bothering Ted knowing he is struggling with his health right now but would like to try to figure this out.

I'll keep everyone informed of my findings.

Bill, I may be all wet here because I am speaking from what my "minds eye" sees and not from practical experience, but I would expect more back pressure from the diffuser at shallow or no depth than from deeper depths. For example, at 10 feet depth, the compressor already has to overcome the static water pressure at that depth. The diffuser might only add an additional tenth psi or something very small to open the slits for the bubble to escape. But I can see where there is no back pressure from water depth, it is going to take something to balloon up the diffuser and cause the air to escape.

I could be all wrong about this. I have no engineering data or practical experience to back it up, just what would seem logical to me. Would be nice if one of the aeration sales experts could come on and give some examples or explanations as I am interested too.

I do know if you connect a dual Matala diffuser to a pump at about 4 cfm it will balloon up when done so on the surface. Did not have a pressure gage installed at the time (have one now). I have not watched it at depth (will this summer when I scuba dive the pond - will try to remember to take pictures) but I would expect the membrane to move very little. Seems I read somewhere it is not particularly good to balloon up the membranes as it is hard on them.

I'm going to run a linear diaphragm pump which looses cfm rapidly at depth, but they are very economical on electricity at shallow depths. My CFM drops in half from surface to 10' and max depth for the pump is only about 12' (where the output would approach zero beyond that).

I've got mine setting out in the shed. If I think about it tomorrow will hook it up and see what happens to the pressure on the surface with the pump turned on.

Again, this is just speculation at this point on my part.

This makes me question if perhaps he accidentally sent you an incorrect diffuser model. Perhaps one designed for a lower CFM rating. As Bill pointed out, the diffuser membrane has holes sized and numbered to allow a range of air CFM to escape without excessive back pressure. They strive for the smallest holes/slits as possible because smaller bubbles for a given CFM has more surface area of the bubbles so moves more water compared to a diffuser that creates larger bubbles. That is why the membrane diffusers are generally considered better than the air stones. They can have better controlled hole size and create smaller bubbles for a given CFM.

But I am speculating. I'll fire up my pump and see what happens on my Matala diffusers.

If a person is trying to force more air through a diffuser that is not designed to handle that much CFM, it definitely is going to have back pressure and is also going to be very hard on the membrane I would guess.

I know Ted pretty well and I sent him an email with a link to this thread about our back pressure problem.
It has always been my experience and preference to have no or very little back pressure (0-0.5psi) on the pump when a diffuser is connected to a compressor. This is very important when building your own diffuser. You ideally want all the air to escape out the diffuser with no pressure on the gauge until you start putting the diffuser in the water. If there is back pressure on a home made diffuser, you don't have enough holes in the diffuser or the holes are too tight/small or both, i.e too much air trying to get out too few or too small of holes. My thinking is why create unnecessary back pressure for the pump??. Use all pressure to operate the diffuser.

For commercial small slit diffusers there will be a small amount of psi needed to inflate or balloon a membrane, but this I think should be low enough to not register on the standard 30psi gauge.

When in the water, then 0.5psi is created for every foot of depth the diffuser descends into the pond.

snrub says: ""but I would expect more back pressure from the diffuser at shallow or no depth than from deeper depths. For example, at 10 feet depth, the compressor already has to overcome the static water pressure at that depth. The diffuser might only add an additional tenth psi or something very small to open the slits for the bubble to escape.""

From actual practice there is no backpressure from the diffuser at no depth. If there is any back pressure out of the water it should not come from the diffuser. What would create the backpressure? Generally it is due to too few holes or too small of holes, or too much air volume trying to get through too few holes. You say ""The diffuser might only add an additional tenth psi or something very small to open the slits..."" This is correct. Very little psi is needed to open the slits, similar to a check valve. Low pressure should be needed to open the valve. At 10 ft the static or water head pressure needed to release air is 5psi. IMO very little extra pressure of force should be then be needed to open the check valve and slits on the diffuser. PSI to open slits plus head pressure, plus tubing back pressure/resistance equals total pressure on the air gauge. Back pressures are additive. Is all this clear as mud???

I talked to him about what I was looking at and then ordered them from his website. There was only one option for the pair of single disk diffusers so that was what I selected.

When I hook them straight to the compressor they ballon up a little but not a lot. No fear of any popping.

I called and left a message for Ted so hopefully I'll hear back tomorrow sometime and be able to get some more ideas.

Snrub, I'll be interested to hear what you find with your Matalas.

Okay I received a response from Ted Lea. He says for the Vertex membrane diffuser, the membrane holder has a smaller orifice in it that other membrane diffuser holders do not have. It makes the Vertex diffusers unique. This is a specially designed "flow control" and adds psi back pressure. It was designed and added to each diffuser to allow equal air distribution on multiple head diffusers especially when the diffuser assembly is not sitting perfectly level on the pond bottom. Once again it proves that Vertex is an innovator and leader in the pond & lake aeration industry.

That's an interesting feature and I am sure helpful. I wonder though about my situation with running one diffuser and how effective that makes it. Maybe I am running to much compressor for what I need.

In the end as long as I know it is working right and does what it's supposed to then it is all good.

Never knew this would get so complex

Now I just need a simple 1/2" check valve at my compressor output. The one I hooked up tonight chattered bad. A Milwaukee Valve .5psi crack pressure.

Suggestions for a check valve. This one should be simple I hope.

Ok, Bill was right on the pressure being zero (except for the new Vertex diffusers having internal orifices).

Absent any internal orifices, my Matala dual diffusers read zero psi (on a 15 psi gage) and ballooned up maybe an inch. I held down one diffuser to close off the internal check valve and could tell there was no pressure then in that side, and all the air went to the other diffuser. The gage still read zero even with all the air going through the single diffuser.

So there is very little back pressure from the diffuser itself, even when out of the water absent any water head pressure. It appears according to Bill Cody's post above Vertex does put an internal restriction to force air to better equalize between diffusers when placed at different depths. This would lessen or eliminate the need for flow control valves to shut off part of the flow to a shallower diffuser (so the diffuser with the lower head pressure does not get all the flow). Probably a simplification for user who do not care to understand the dynamics of pressure and flow in their system. IE makes it more idiot proof.

I think I need to get my other diffuser base made up so I can get the other Vertex diffuser in the shallow portion of the pond and see what the pressure does under real use.

10psi still seems high to me for just the one diffuser running in the water at 9' especially as that is with the pressure relief valve going off when set at 15psi relief.

An inch of ballooning is about what I experienced with both the Vertex diffusers so that is the same.

Here are some additional threads and information that might be helpful.

Pressure calculation thread

Aeration simplified thread

Water head pressure table
Note on the table, it is .43 psi for each foot of depth. As esshup pointed out in one of the other threads linked above (and Bill Cody mentions in his post), .5 psi per foot is a good rule of thumb figure to use as it allows for a small additional back pressure from friction in the supply line and diffuser.

You are getting me excited about getting my system back in the water in a more permanent fashion than it was last fall. Getting that time of year.

Perfectly clear, and you are absolutely correct. I was incorrect in my thinking that head pressure would make a difference. It does not.

Maybe I am still not understanding things correctly. I am trying to understand how I get 10psi on my gauge right of the pump and the reading at 9ft water depth.

Is the Vertex not designed to be used as a single disk diffuser? Or as a single disk is it meant to be used with a lower pressure compressor?

At 9ft depth, .5psi per foot I should be running about 4.5psi at the pump. However with the single Vertex I get over 10psi at the pump and setting off my pressure relief valve. However if I pull the diffuser up and swap out to my old stone diffuser I am about 5psi or just over.

What does it read when you pressure up out of water? Your getting back pressure some where either line resistance or diffuser/depth/line length/resistance.

Could also be the Guage or popoff relief

With the Vertex I get 10psi+ in or out of the water. At the pump or at the end of the line.

With the old stone diffuser I get 1psi or under out of the water and around 5psi in 9' of water.

Call Ted..

Notice on this page the water volumes moved are based on 1 cfm per disk. I'm wondering if you just have a lot more air than the orifice in the diffuser is expecting.

Lifting rates

Like Bluegillerkiller said, call Ted.

The holes in the stones are much larger than the slits in the membrane, that's why you are seeing less pressure with the stone.

I was simply answering the question that was asked.

I do think I may be feeding the diffuser more than it is designed for. Looking at the setups that Ted sells and the systems put together buy Vertex on their website, they are showing a 1/3 HP single piston compressor with an output of 2.3 cfm at 5psi operating pressure for the 1 or 2 diffuser systems.

My compressor in comparison is putting out 4.34cfm at 5psi operating pressure and even if it goes to 15psi is still over 4cfm. Double what the single disc is rated for.

My guess is I am running too much compressor for one disk. As I've researched a bit more on the Vertex sight, they don't even jump to a compressor with the ratings of mine until their 4 disk system for lakes. All their pond systems run off 2cfm max with smaller compressors.

I guess with the more efficient diffusers less compressor is needed which is a good thing. I probably didn't research and ask enough questions prior to buying the new diffusers but that is ok, I am learning and believe can make work what I have.

I have left a message for Ted and when he feels good enough to call I am sure he will. I am pretty sure though with everyone's help here things are beginning to make sense.

You always have the option of "bleeding off" excess air. This just kind of wastes some energy.

Another option during your "remediation phase" where you are wanting to get a lot of turnover is to simply tee in your old diffusers with the new. Instead of bleeding air off to the atmosphere, just split it up and run the excess through your old air stones and get some added water movement from them. If after trying it you feel it is moving too much water, take the stones out of the pond and use the bleed off method.

The other option is to simply use a different diffuser that can handle the volume, or add more of the Vertex diffusers. Maybe two doubles instead of two singles. Or if the membranes can handle additional air, drill out the orifice to a larger size.

Just some ideas to consider. Sometimes there is more than one way to skin a cat.

I was thinking that the 3/8 line itself was causing some of the restriction, but that seems not to be the case.

I agree about either bleeding off the excess air or adding more air line to put in the stone(s) that you already have.

If you take a look at the lifting chart on the Vertex site, you'll see that when the diffusers are arranged together, they help each other with the lifting rates - i.e. 4 together have more lifting rate than 4 singles.

Also, if you take a look at all the different systems that are offered, only the smallest one has a single diffuser - all the others have at least 2 diffusers hooked together.

I run a single diffuser in the winter in 3'-4' of water, and run it at 5-6 psi. I want a large boil to create a large surface distrubance to keep the hole open. I just bleed off the excess air because the pump puts our a LOT more air than what I need for that single diffuser.

I was somewhat concerned about the 3/8" line but it is only about 50' worth and Ted didn't seem concerned in our initial conversation before I ordered everything.

I don't mind running the extra diffusers I already have.

My thought now is once the pond is back in shape, I can run the 2 Vertex diffusers in the 12' section and one of the old diffusers in the shallow area where we swim to help keep that area nice on the bottom.

I can them run my other old diffuser on the other side of the pond at 3' for the winter and create a good boil to keep the ice open without having to bleed off air.

Probably overkill but don't see any reason not to go this route unless I am missing something.

We'll Nate, at least when you get this figured out you will know all there is to know about those things!

This is good stuff and lots of great info. I drive my wife nuts sometimes because anything I do I seek to gain all the info possible, go all out, and don't always keep it small and simple. This is just the next adventure.

Keep in mind what esshup was saying. You want your fusers if you have more than 1 about an inch away from each other. The closer they are the better up welling you will have with you water getting to the surface to get the D.O. your after. 1 by itself in the winter is fine just to keep the ice melted some but out in the middle of your pond I would have at least 2 in a 1 acre pond. I have a 1 acre pond and my 2 work great. I am running a Gast 1/3 hp pump in 8ish foot of water at 4.5 psi. I am not running vertex fusers though. Vertex fuser have very very small slits in them so it would stand to say that your pressure may be a bit higher with them. I have 2 Vertex fusers I plan on changing to and am going to see what my pressure is then verses what my pressure is now. I am curious to see how much more pressure it will put on my pump.

RC

So, I got a few more connections and brought my 1 Vertex diffuser in out of the water. Put a T connector on and my psi out of water, hooked straight to my compressor dropped to 1.5 psi.

Based on all the ratings I am seeing on these diffusers, one diffuser is rated at 2 cfm max and the pair together is rated for 4 cfm max.

Based on the specs of my compressor and the design of these diffusers, and through some testing, I am convinced I need to run the two diffusers together from one air line.

Now, I just need to make another run to the store to get another elbow so I can get everything set right and back in the water for a final test.

I am hoping I can run these two alone in deeper section of the pond and then run a single diffuser at about 3' in the winter. The two diffusers will be about 3" apart the way I was able to mount them.

Certainly getting closer to getting this setup running thanks to everyone's help here.

I'll continue to convey my findings in hopes that this has been beneficial to others besides myself.

Dropped the two diffusers in at about 9' depth. It is now running about 6.5psi. When I turn my other diffuser valve from my ring diffuser open about 1/4 it runs about 5.5psi.

So, all is good and I should have paid more attention to the specs on all the equipment I have.

Still more to learn and play with. Continued thanks.

Glad you got it figured out. And thanks for sharing the information so we all can learn.