Pond Boss Forums AERATION Systems questions Big Max vs Home Built Disc (With Pics)

My buddy and I both put in aeration systems last week. I drove to his house, helped him install his, and then we drove back to my place and installed mine. We went different directions and ended up with a nice comparison for people who are considering purchasing various systems. We're both members here in case anyone has future questions.

System 1 (tlogan)

Pond
This pond is roughly .4 surface acres with a max depth of about 9 feet. It is roughly kidney shaped and there is a slow grade into the pond on all sides with the deepest point in the center.

System
He purchased the Gast 82R rocking piston pump from bluelooney on eBay. He sells lots of rebuilt Gast and Thomas pumps. Here is his ebay store page: http://stores.ebay.com/cdesurplus?_trksid=p2047675.l2563

The rest of the system was bought piece by piece from Bill Cody. Parts list as follows:

• EPDM Membrane style 9” disk diffuser mounted on a lawn tractor tire
• 60’ ½” weighted airline
• 100’ poly pipe ½” (buried)
• Air filter-custom made to fit small engine filter
• Liquid filled pressure gauge

Total system cost was right around $330.

With no electricity near the pond, the pump is housed inside the adjacent pole barn. We trenched poly pipe beneath the soil and connected to weighted airline below grade using stainless steel hose clamps. The disk diffuser is mounted in a 7” rim lawn tractor tire which perfectly mounted the 9” disk diffuser. We cut holes in the sidewall to allow air to escape so the tire would sink to the bottom. A $5 mechanical outlet timer controls aeration on time to 5 hours/day.

Pictures
Overview of the pond.


This is the pump he picked up from bluelooney. It's a Gast pump with spring feet and a really nice air intake filter.


He didn't have power out by pond so we trenched back about 100' to put the pump in the pole barn. We buried poly line, and connected to the weighted airline at the water's edge.


Another shot of the trench heading back to the pole barn.


We forgot to get a picture of the diffuser before sinking, but it's essentially a standard 9" membrane disk, but is attached inside of a smallish lawn tractor tire. It fit perfectly. It's like a rear tire for a zero turn lawn mower. We attached poly line so it would float, and cut/burned it off just above the water. We'll add a picture if we ever need to pull it up for service.

Here's a picture of the diffuser with the pump running. At only 8' deep, the turnover isn't huge, but we're seeing lots of good bubbles and everything seems to be working fine.


System 2 (jdhaines)

Pond
It'll be the easiest to simply link to my main information thread on my pond.

TL;DR - 1/2 acre, bean shaped, ~21ft deep in the middle, ~18ft deep at the end (locations of the two aerators described), used for our drinking water.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Main=29432&Number=377175

System
I purchased a complete system from http://www.fishpondaerator.com/ through eBay. The system name is "Big Max." I paid $388 which included everything including 150ft of weighted airline and two diffusers making the system more expensive. It included all the hardware, an intake filter, and a nice Thomas wobble double piston pump. It also has a 1 year warranty on the entire system which made me feel better. The ring diffusers looked almost like rigid soaker hoses and didn't have check valves...although in a week of use it starts right away with no issues and they told me that this system doesn't need check valves. I can't argue with them because The bubbles form right after start-up. Here is the kit picture.



I know that this system and ring diffusers don't get a lot of love here which is the main reason for the comparison. See below the pictures for our discussion on this vs the normal membrane diffuser.

Pictures

Overview of my pond from the air. The pump is installed on the small concrete pad at the bottom right of the pond in this picture.


I built a frame on the pad leaving a 1" gap around. I used concrete studs to secure the frame, and more studs to secure the pump. I isolated the pump with rubber washers, and used some metal strap to bolt it down.


Here is a picture of the mock-up for the outer "house." The house will sit over the frame and have vents and a fan for cooling as well as provide shelter.


Here is the house during construction. I'll upload another picture when I finish it. I still need to paint it and install the vents.


Here is a diffuser under construction. We got two old free tires, drilled holes, and used heavy zip ties to hold the diffuser ring in place.


We then drilled another hole through the outside of the tire and fed in the air hose because of the direction of the diffuser nipple. We also drilled holes at the highest point on the sidewall to allow air to escape. The diffusers sank easily. We used poly rope tied to the tire and cut/burned the tip about 1' about the water. It floats so you can see the tail of rope floating in the air turbulence. We should be able to retrieve it easily if we ever need to.


Finally, here's a picture of the two patches. The left one is in the second lobe of the pond, mostly centered, and about 18' deep. The right patch is in the center and is about 21' deep. The one closer to the pump starts bubbling probably 5-8 seconds after pump start, the second one starts probably 10-12 seconds after pump start. Lots of turnover and bubbling.


Discussion

Noise
The Gast pump is slightly quieter than the Thomas pump. I will say, however, that noise on this forum is completely overrated...or we got very lucky. All the talk of noise abatement, insulated boxes, coverings, etc seems completely wasted. These pumps are quiet. If you don't want to hear it at all, then you'll need a box. But even running open to the air, I can't hear them unless I'm within probably 10' or so. We had both expected these to be loud rattling monsters and it just isn't true. I don't have a rotary vane pump to test, but these piston pumps have surprised me with the noise level.

Effectivness
Honestly after seeing both systems installed...I don't see a big difference between the two. I realize on paper the disc diffusers should work better, but both systems produce a comparable amount of bubbles and turnover. Remember, we're not comparing apples to apples because the disc is at 8' and the rings are at 20'...but I'm very happy with the performance of the "bottom of the barrel" Big Max system. At the price point and convenience of buying one time...with a 1 year warranty I wouldn't hesitate to recommend this system.

Josh thanks for capturing all this and making the post. Will be great to hear others thoughts/comments on the subject. Feel free to ask as many questions you wish.

Josh - question. Given your depth differential between the 2 diffusers I assume you have a manifold that controls the pressure to the 2 lines?

Great post by the way...good pics and useful info.

Nope. There wasn't a manifold included. The top of the pump was drilled and tapped for two outlets, one inlet, and one pressure blow off/burst which was already installed. Each of the outlets has one brass nipple fitting which is threaded directly into the pump and is clamped directly onto the weighted airline. This is the way it was designed. Based on my best measurements there shouldn't be much more than about 3-4ft difference in depth between them. But the 18' one uses about 45' of weighted line, and the 21' one used about 80'.

I guess that height difference isn't enough to matter? Someone smarter than I will likely be able to give more info...I was under the impression that if there was any sort of 'significant' (I think this is the key, I just don't know what 'significant' equates to in depth) difference in depth between multiple diffusers off the same pump you had to use a manifold.

Nice job JD. The only things that stood out to me using the tires would be that the bubbler hose loses a lot of efficiency being up against the tire instead of a few inches above. Also that unless the tire is buried into the bottom, currents will erode under the tire and suspend dirt in the lifting water column...or worse, dig a hole under the tire to let the entire assembly to flip on it's side.

Along those lines Rainman, I have a commercial vertex double diffuser and it has its own plastic box that it sits on. The box is about half full of stones to help weigh it down. The box is only about 3" tall (by memory, Sue who sold it to me would know exact specs) I do wonder how soon the sediment builds up, and the bottom starts getting closer to the under side of the diffusers?

I was thinking of pulling it up (my floating bobber that marked the spot came loose in a high water event, the rope is still tied on but sunk, I think I can snag it with some type of pole or something at which time the floating rope as in this post would be a good idea) and getting it higher. A tire seemed like a good idea but now I'm wondering if I might use one of my storage totes. I totes that are about 20" high, inside dimension about 36x15 or so. I would drill holes in the side so water can get in, flip it upside down and figure a way to fasten the diffuser to the bottom of the 'tote' That should get me a firm base and raise it about 20" or so. It will settle in the muck over time but at least I'll be 18" or so off the bottom.

Other option is to be faithful about pulling it up in the spring, cleaning the membrane (how often to do that?) and letting it settle back naturally on top of things again.

Good point about the tire.

I'm not sure how much any loss of efficiency would actually matter. Maybe a little air from the bottom side of the ring would enter the tire sidewall...but we have holes to let that air out. If it fills it would just run out and up. Even if I lose a little efficiency, it should still function fine.

Also, I'm not sure how there would be much sediment built up...but even if the whole thing got buried, the air would still rise. If I look out and see that there is relatively little air or no lifting, I guess I'd swim out and pull the rope up to shake it off a bit? I think I'm just going to run it and not worry about it until I see some sort of problem at the surface.

Trent and I talked today and I wish we would have sunk the two diffusers in my pond temporarily just to see the difference at the same depth and side by side 20ft apart or so.

JD, is that some blue dye in your pond? Can you share make/model of the dye and roughly how much it takes to achieve that shade of blue? It looks nice!

If others have advise on this that would be great.

Never underestimate the power of constantly moving water. A poorly designed/placed diffuser can dig a hole several feet deep pretty quickly. With the circular design of the bubbler tubing, water will get pulled into the center because of the low pressure area developed. the most likely place for that water current to flow will be from under the tire and up the center, possibly pulling a lot of soil with it.

Canyon, a diffuser can be low, as long as there is a flat base that won't sink into the bottom. Plus, that base protects from the stronger currents close to the diffuser from eroding the bottom. If there is 12" of silt the base sinks into, then you'd need more diffuser clearance. I like a diffuser about 12"-20" above the bottom silt if there is a small base, has legs, or it is open bottom.

I just used plain aquashade. I tried an off-brand and never had good luck with it. This year I poured about 3/4 of a gallon directly onto the ice in a big patch. As the ice melted it flowed into the water. I'm pretty happy with the color.

I'm hoping with the aeration I can get away from using the coloring, but I knew I wouldn't get the aerator in right at ice melt, and I wanted to stop the early algae bloom that happened last year...or at least reduce it.

The aquashade has another benefit for us. We drink the water in the pond. It gets filtered through multiple filters and uses chlorine bleach as part of the process. When the system is working well, the water is nice and clear. But with good amount of aquashade in the pond, the water in the showers and toilets becomes a noticeable blue when the chlorine system isn't working correctly. A month ago our water started turning blue and I checked the Stenner peristaltic pump and found the tube to be worn and the chlorine levels low. It's a nice early warning sign. Once the aerator is working well, I may go back to the off-brand blue dye just for the chlorine check and looks.

There is a noticeable difference in the thickness and concentration of the blue dye in aquashade versus the off-brand. But the aquashade was noticeably more money.

Hope this helps.

EDIT: I'll add that the System 1 pond also has aquashade in it, but isn't nearly the same color. I'm not sure why mine takes that particular shade of blue...it is pretty though!

Ring diffusers make nice very fine bubbles until they plug up from bacterial, fungal and slime growths in the irregular porous surface. Too small of bubbles and poor design of the surface material can cause undue problems with clogging. Then how does one clean them? Some have tried the fine porous hose idea including me and abandoned the idea after years of use. As the diffuser plugs it puts more resistance on the pump which shortens pump life span. These two features does two things for the seller; sells more diffusers and sells more pumps. What appears as a good deal may not be true in the long term. The package system example also did not have a pressure gauge which is an important item when trouble shooting system problems and for monitoring normal operating conditions.

Water column lift depth is significant between the two systems. A doubling of the column height between the two systems is not a fair comparison.

Surface boils of the ring vs disk diffuser will appear different but it does not truly reflect the volume of water that each lifts to the surface. Ring diffusers produce a different style of boil than the disk. Boils for ring diffusers at the surface will appear much more effective than the disk. Testing has shown the center column area of the ring diffuser has turbulent counter productive internal flow that tends to work against itself in terms of total water movement or circulation. Lifting column of the disk diffuser is a more solid or uniform bubble mass which results in more effective water movement. Run some test for proof.

Rainman has some good points about your setup. I guess over time we will see what happens. Keep an eye out to see if your water starts to get dirty looking versus what your used to. That would be a direct indication that your bottom fuser it pulling up muck from the bottom.

My fusers are about 6 to 8 inches off the bottom but I have a large side of a computer on the bottom that I have them attached to. So I don't get any stir up issues.

I have a gast rotary vane pump 1/3 hp and its not that loud either. At ten or 20 feet I can hear it, but at 80 feet away up by the cabin you really, really have to listen for it!! There not bad either! Hey great post and I love the compare thing you did!! Keep us posted at to how yours works over time!!

RC

Also as Bill alluded to, as the pores clog, the bubbles get larger as they coalesce on the diffuser or right after leaving the diffuser, so they have less lifting as fine bubbles. So, the diffusers will change in performance over time. By exercising and cleaning the diaphragm diffusers you can keep the same performance level over time. With the ring diffusers, not so much because as Bill said, how do you clean them?

How do I clean my vertex fusers? I can't flex them as I only have one output from the pump and I understand to 'flex the membrane' you have to turn off air to that line, and then turn it back on to that line or something like that?

I hope to pull mine up and inspect the membrane. How do you clean it? Just rub it with your hand or a cloth? i'm sure you don't want anything scratching it...

Canyon the flex way can work but to clean your membrane all I do is take a soft hand brush and lightly scrub the top of the membrane. I like to try and do this over the boat while the membrane is still in the water that will it washes off nice while your doing it! Then I would go flex again a couple of times and then let it run for a bit. That should clean it off fairly well.

RC.

As the pro's will tell you, cleaning the membrane diffuser is very important for all the reasons mentioned above. Most membrane diffusers are not annually cleaned because of the difficulty to raise the assembly off the bottom.

Full disclosure: My daughters own the business/ web site of the product link I'm posting here....Airanchor.com

This is what we use. Can be used with any diffuser including a Vertex. It allows the pond owner to lower the diffuser assembly like an anchor using a rope. The attached harness is float rope and stays "standing" in the water. Retrieval is done using a minni grapple in any depth of water.

Moderators - I hope this was ok to post. If not, my most sincere apologies!

How do you 'flex' it RC51?

Ted Lea had a post describing how to flex membrane diffusers. I lift my membrane diffuser, unscrew it an take it inside and scrub it with a fibrous pot scrubber. For membranes in shallow clear water winter operation, I have seen strands of algae grow so tightly to the membrane a putty knife would not remove all of it. I had to use a razor blade scraper. A deep water diffuser in fairly turbid water (vis 2-4ft) will generally only have silt and maybe a little carbonate deposits on the membrane. In higher alkalinity water the carbonates will form on the pore openings that can cause the pore to grow shut with mineral and bacterial deposits. Iron will also precipitate on the membrane.

Thanks for the write up.

Mr Cody goes that extra mile to clean his membranes. I guess I kinda cheat a little and just pull mine up at the boats edge clean it off and drop them back down. Believe it or not the membranes are pretty tuff!! As Cody says he scrubs his with anything from a pot scrubber to a Knife if need be!!

Flexing a membrane is nothing more then putting some extra air to it for a few seconds to help clean it out.

This works well if per say you had a nice size pump and you had a gang valve on it to push all your air to one fuser for a few seconds and then all your air to the other fuser this is called over flexing the membrane just enough to help clean it out some. Or at least that's what I believe it is?? Don't quote me on that but I think I am in the right direction. If not please someone correct me.

RC

OK, I can't flex mine as I have no way to control flow to one or the other membrane.

I do need to get a floating rope or something for easier access and cleaning yearly.

I bet I have some calcium deposits on mine as we do have some hardness in the ground water.

I do have a fair amount of iron as I discharge my iron remover system bakflow/regeneration water into the pond

Turning the system on and off also flexes the membranes. But, it's not as good as what Bill does to clean them.

I typically float a duck decoy over the diffuser assembly. Then go out in a boat to pick up and clean them in the pond.

I have seen where a duck decoy has spun around the same direction in the aeration boil to the point the twisted rope lifted the diffuser off the bottom.