I have a 1/3 acre pond that's 10' deep I'm trying to setup an aerator for. Its about 500' away from electricity. I was going to try to run power out to my pond, but found on this forum I could just run the air line. I just ordered a Vevor kit that has a 1/2 hp pump, 100' weighted airline, and 10" membrane diffuser. Maybe that was a mistake, I don't know.

My question is what air line would be best to cover the 400' underground? The 3/4 100psi black poly is the cheapest and in stock. Would 1" be better (would have to be ordered), or a heavier pipe? I plan on using a sub soiler behind my tractor to bury it.

You may get a couple different answers but IMO 3/4 black poly should be good enough for pushing air 400ft. I'm not familiar with the Vevor kit. A link to it would help more with answers. There are some very informed number crunchers here that hopefully can add some good information to this thread topic. There are chart/tables to find the resistance to air moving through tubing. One such chart was referenced this past week. IMO the most important factor is how much psi does the compressor create. The lower the compressors psi the more important airline diameter becomes for pushing air over 300-400ft.

There's not a lot of info on it, I'm guessing it's a chinese copy of some other pump. Just says its 4.8 amps and 4.7 cfm. I think it might be oversized for what I need, but I figured that would give me some buffer to push air that far.
https://www.amazon.com/gp/product/B09SZ8TZ23/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

My main concern with this system is the underwater weighted airline. IMO it is undersized for diameter at 3/8". However this pump that produces at least 25psi (50ftdeep) rating. Airline of 3/8" ID for rocking piston will work but I think it would better perform with 1/2" or 5/8". Long term the for life of the pump larger dia airline would be better for less stress on the pump. Mechanical stress is what wears parts out. The Vevor company website gives more options. Contact them for if larger dia airline is available or ask to buy the system without the airline then buy airline somewhere else.

3/4" will be plenty. Don't even consider 3/8". Too many problems with backpressure and it freezing solid in the winter

All the above is very good advise according to crunched numbers. 3/4" main long line and 1/2" to 5/8" for the diffuser should work well. I have estimated some differences below.

Assuming the following for the completed setup with 3/4" main line and 1/2" diffuser line and a diffuser at 10 foot deep...

Assumptions...

1.) The pump will put out between 2 - 4 CFM at the diffuser.
2.) Running between 8 and 15 psi.
3.) 0.5 to 1 psi to operate the diffuser
4.) Zero losses for valves and fitting since it is a single pump with a single air line (no constricting fittings or valves).
5.) The diffuser line will be 100 foot long.

Pressure loss through the 3/4" line at the low end of the above pump pressure assumption and the high end of the
CFM assumption from...

https://www.engineeringtoolbox.com/pressure-drop-compressed-air-pipes-d_852.html

yields about 1.7 psi. This is the extra pressure that it takes to push the air through 400 foot of 3/4" line given the best conditions of the assumptions.

Do the same for the 100 foot of 1/2" line...

Yields about 3 psi to total 4.7 psi using the best conditions of the assumptions.

Do the same for the higher end of the pump pressure and lower CFM assumptions and you get...

0.2 psi for the 3/4" line and 0.5 psi for the 1/2" line to total 0.7 psi.

The point of the above exercise is to estimate the back pressure on the pump without knowing the actual numbers, using a range of educated guesses. With the above assumptions and quick calculations...the pump would see a back pressure from the 3/4" and 1/2" lines of 0.7psi to 4.7 psi. Lets use the average for a comparable number for later...2.7 psi.

To summarize, the above mumbo jumbo estimates that the system would have about 2.7 psi of back pressure from the 3/4 and 1/2 hoses alone.

If we do the same thing for 1" line and 5/8" line...we get 0.8 psi

How about 3/4" and 5/8" lines? We get 1.5 psi.

So, you can knock almost 2 psi off the pump by using 1" & 5/8" compared to the 3/4" & 1/2". That's a very nice reduction.

You can knock over 1 psi off the pump by using 3/4" & 5/8" compared to the 3/4" & 1/2". That's a good reduction.

A piston pump is a very good pump style and can put out more pressure than the other options (Rotary vane & Diaphragm) hence producing the CFMs you need without killing the pump. Knocking the pressure requirements down on any compressor pump is a good thing for the life of the pump, however.

Once again, the above mumbo jumbo is just to back up the previous good advise from those that know without having to run some numbers...

3/4" & 1/2" line will work with a piston pump.

3/4" & 5/8" works much better.

1" & 5/8" works even better, but would be overkill, in my opinion, given the extra money that would have to be spent for that last 1 psi. This scenario might prove to be a reuired for a rotary vane or diaphragm pump, but not the rocking piston.

Thanks for all the info. Sounds like most of this should work, I'll just forego the 3/8 weighted line. I may just get more of the 3/4 poly and try to weigh it down, unless that would cause some other issue. I've got plenty of brick and concrete block. If that fails or is too big of a hassle, I'll order some 5/8 weighted. It just seems kinda pricey for what it is.

Your two main concerns for using 3/4" poly underwater. 1. It will take close to 3/4lb of weight per foot of airline; 5/8" ID requires 0.5lb/ft, thus 100ft weighs 50lbs. . 2. Don't put extra weight on the airline just enough to hold it down because you should be lifting the diffuser out each year and cleaning it. Pulsing the air to the diffuser often does not adequately clean it for good efficient bubbling. Membrane diffusers should have proper maintenance which means a scrubbing each year usually at the beginning of the aeration season - spring.

Purchased weighted line is the way to go. When I first put my system in, I thought..."it's in, I like it, and that task is done". Over the the next few years, I have moved my diffusers a few times, changed the height of a few of them, and pulled them for cleaning. I can't imagine what it would have been like diving for cinderblocks or trying to drag home-made attachable weights around the pond.

I second this opinion. I used mostly sinking hose but a few places used black plastic pipe under water to cheapen the cost up some. Very short sighted. In the ground going to the pond plastic pipe is fine. But as soon as you hit the waters edge go to the sinking. You can thank us later. I know it is expensive for hose but it is not the place to cut costs.

Been there, done that.

I am using the poly hose for inside my pump box, outside of it before it goes in the lake and also within the diffuser cages I built. I noticed this weekend that the majority of connections where I used hose clamps were leaking air. At the elbows, the tee, the valves, much of it had leaks that weren't there when I first set everything up.

None of the weighted hose connections had leaks though, only the poly.

I used soapy water around all of it to pinpoint them. When I assembled everything, I tightened the clamps with a screwdriver. I thought I had cranked them down well too. I used a ratchet this time and stopped all the leaks.

Just thought I'd throw that out there in case anyone else finds they have a similar issue while using clamps and that hose.

It is best to use car heater hose (NAPA etc) for inside the pump shelter and to get out of the shelter to the ground connection for black poly underground line. Rubber heater bends around tight curves easily, withstands the heat and resists kinking. The problem that I have with the black poly in the shelter is after time you can't get the black poly off the fittings. You almost have to cut them off when you have to do any maintenance on the compressor . With the heater hose it always easily pulls off all connections.

A couple ways to reduce or eliminate the problem of leaks of plastic tubing at a connector. One is to use two hose clamps with the screw turned 180 degrees of each other. The other is to use a cigarett lighter and slightly warm an inch or two of the tubing. Then when it is still warm, slip it over the connector and tighten the clamp. By warming the plastic it will form fit around the grooves in the connector.

Looks like 5/8 weighted hose is what I'll go with. Using rubber hose off the compressor is a good idea too. I've already got a ton of the crimp type clamps, figured I'd double them up. I was thinking about getting a 15 psi pressure gauge and relief valve but not sure if that's really necessary. My biggest concern now is getting the line buried with my tractor.

The water heater hose inside the pump house sounds like a good idea to me. I just used plastic in my pump house and it has worked but I can see where the heater hose would be better. It would be more flexible than the more rigid plastic so easier to hook up if a person needs a bend. I used some really flexible plastic hose (from the hardware store) for the short run from the pump to an elbo to the plastic tubing, but it gets squishy from the heat of the air coming out of the pump (vane type air pump). It has never given me any problem but I have wondered about it failing some day because of the heat. Heater hose would eliminate that potential problem AND be flexible to hook up easily. Sounded like a great idea to me and will be considering it if I ever change/replace what I have.

I got my 3/4 line ran with my tractor, it worked surprisingly well. Temporarily hooked it up to test until the line blew off (didn't have the right adapters). I still need the weighted 5/8 line, does anyone have a good place to get it? I'm seeing like $180 for 100'.

Unfortunately with the increased oil prices, that $180/100' is about average for the weighted 5/8" line. The last 2 years has seen an increase of about $50/100' of weighted airline.

I bought mine from esshup (above poster) at...

https://shop.hoosierpondpros.com/Vertex-BottomLine-Tubing-058-ID-100-roll-100BL58.htm

Competitive pricing, a great PB forum contributor, and good service.

I finally got my 5/8 weighted hose and finished setting everything up. It's working great and I have a good boil going. Is 5 to 5 1/2 psi of backpressure reasonable for this setup? Just wondering if I should add a second diffuser to reduce stress on the pump.

That's a good question. From the data that's been posted, it's impossible to tell unless I missed something. We need to know how much water is over the diffuser membranes. (water depth)

Didn't check when I put it in, but should be right around 10'. Just want to make sure this is a safe range for constant use with this kind of pump. Or should I only use intermittently to save wear?

There is less wear and tear on compressors if you just leave them run vs start/stop. Rule of thumb is .5 psi back pressure for every foot of water depth over the diffusers.

I have no idea what the operating psi of your compressor is, we don't sell those. Look in your owners manual to see what they say. Read Quarter Acres response above and do the calcs that he posted.

If your diffuser is at 10 foot deep and your pressure is 5 to 5-1/2 psi, you have a very well balanced system with respect to the fittings, line size, and diffuser. Adding an additional diffuser will not reduce the back pressure (which reduces pump stress) given the additional diffuser would be located at the same 10 foot depth. The only way to reduce the backpressure at this point is to move the diffuser into more shallow water which will reduce the amount of turn over you get.

I'd bet you are at a very good place with the pressure it is running at. The only way to add to this conversation would be to see a pump curve for your unit, but I could not find on on the net. I did find that its maximum depth is 50' and that would correlate with about 21 psi...so, you are operating quite a ways from its max. I would want to know how much CFM it pushes at that back pressure (5 to 5-1/2 psi). If it is near the 4.7 CFM max, it might be overdriving the diffuser. Diaphragm diffusers are pretty robust and can take some abuse. AND, they sell the kit with only one diffuser which may tell us that the diffuser is good for what the pump- can put out.

I'd say your pump is in a good place along with your whole set up given it is sized for your pond volume.

Just Dave, can you edit and fix the link you gave above to the pump? Or report a new post with a working link? I'd like to research that pump some more.

Thanks

I think I'll leave it alone and let it run then. Thanks again for all the help. It's already making a big difference in the filamentous algae in my pond.
https://www.vevor.com/pond-lake-aer...pump-100-tube-10-diffuser-p_010324435448
That is the seller, it just happened to be a couple bucks cheaper on amazon at the time.

I agree with QuarterAcre's reply posted above. Good answer! " Adding an additional diffuser will not reduce the back pressure (which reduces pump stress) given the additional diffuser would be located at the same 10 foot depth. The only way to reduce the backpressure at this point is to move the diffuser into more shallow water which will reduce the amount of turn over you get.".