Pond Boss Forums AERATION Systems questions 1/10 Acre Pond - DIY Aeration options

New to this wonderful site, have done lots of reading and learning! Bought a house that has about a 1/10 acre pond approximately 10 feet deep when full. Sides are relatively steep as far as dropping off. Was looking back and saw a few DIY systems using an ECO 7 pump. Given that my pond is relatively small, I was thinking of going with the ECO 5 with two 9" diffusers. I would have the pump about 5' on the bank of the pond, electric is already there. Not knowing calculations for this type of thing, was hoping someone could tell me if this setup would work. Not sure I need two diffusers either??? Appreciate any help with this! Matt

What's the psi and cfm on your pump? I would think 5 psi would work judging by snrubs info.


Thanks snrub for the info it was helpful for me.

I can tell you what I am doing with my 1/10th acre sediment pond.

I'm using a Pondmaster AP100 and splitting the air. One line goes to the 1/10th acre sediment pond and the other line goes to a 1/20th acre forage pond. The single pump supplies air to both ponds. Each pond has a single Matala 9" round membrane diffuser. I use a water hydrant splitter as a manifold valve to shut down part of the air to the smaller pond so the larger one gets more air.

There appears to me to be plenty of air for both ponds. The AP100 is a 100 liter per minute pump (at zero back pressure, falls off to zero cfm somewhere around 6 psi with about 2 cfm at 4.5 psi). Both ponds are around 8' deep.

I would think the pump you are considering should be plenty adequate, but I'm no expert.

It appears my AP100's will last about 9-12 months of continuous running before needing a rebuild kit. I have 5 of these pumps and run 4 continuous (one for a spare) and so far have had to rebuild 2 of them. Kits to rebuild are about $15 and takes me about 30 minutes. If a person was proficient at it it should take about 15 minutes.

I think the Eco5 might be about the same size pump.

Edit: The Ecoplus 5 is an 80 watt pump and the AP100 is 100 watt, so the Ecoplus 5 is probably smaller. I still think it would be adequate though. You will be asking about all you should from a linear diaphragm pump at a 10' depth though. That will be pretty well maxing out its capability. The AP100's I'm running in my 3 acre pond are operating at 9-10' depths. One 9" diffuser is plenty in my 1/10th acre pond.

Here is a performance curve for a Hako linear 100 LPM pump, which should be similar to my Pondmaster AP100's (Pondmaster does not provide a performance curve for their pumps )

It will give you an idea of the drop off of air flow as water depth increases. That is the down side to linear type pumps - performance falls off with depth. The up side is they are VERY energy efficient and low cost and as long as they are used within their capabilities can operate at very low electrical costs.

performance curve of a 100 lpm pump

The jury is still out if overall these pumps will be any cheaper to operate in my pond than a more conventional rocking piston or rotary vane pump over say something like 5 or ten years. The electrical cost should be far less. But my maintenance and capital replacement cost do to shorter life of the pumps may eat the electrical savings up. We will see.

Here is a thread you might find helpful.

pressure calculations

I would verify the this pond is 10ft deep. Measure the depth when full. It is pretty difficult but not impossible to build a pond this deep in 1/10 ac. Sides would have to be 2.5:1 slope. At 10 ft deep you will need at least 5psi to get air out a diffuser on the bottom. Most linear pumps struggle to do this. You would only need one membrane diffuser in 0.1 ac to get very good circulation (turnover) a few hours a day providing the diffuser is receiving at least 1cfm.

Ever heard that expression of something about sticking your nose in and getting it cutoff, well here I go....

IMHO and I repeat IMHO, air flow requires a positive difference in pressure between the source and the exit. Pressure rises at 1 PSIG for about every 27.7 inches of water depth. For example, a pump capable of producing 5 PSIG will pump air in a decreasing amount to a depth of about 11.5 feet but will produce no flow at that depth. It will acheive equilibrium. Any pressure the pump can produce in excess of 5 PSIG at 11.5 feet (minus line and diffuser pressure drops) will determine the actual air flow rate thru the diffuser at 11.5 feet.

My nose hurts already!

The linear pumps I am using have an 11' maximum recomended depth, but in my opinion that would be really pushing it. My max pond depth is 10' at full pool (bout 10.5 right now!) but also the diffuser base is sitting up probably close to a foot from the bottom. So in reality even though the depth is 10' the pump is looking at about 9'. I get good air flow at that depth and according to the performance curve for a similar pump of another brand I should be getting in excess of 2 cfm.

To a vane or rocking piston pump, talking the difference of 8 or 10 or 12 feet depth would make very little difference in flow rates. These type pumps are positive displacement and the drop in performance is due to any slippage of air around the sealing surfaces as well as the displacement vs the amount of compression (much like the compression ratio of a car engine).

But a linear compressor is quite different. They use a diaphragm with a solenoid style electric motor that pulls the diaphragm in one direction then coils on the other end pull the diaphragm in the other direction. The maximum pressure that the compressor is able to develop is related to the power in the coils in each end of the linear motor. The coils can only pull so hard and the travel of the diaphragm limits the volume of air. This happens at a frequency equal to the AC frequency of 60 times per second in the US. As back pressure is exerted against the diaphragm, this back and forth pulse does not pull the diaphragm as far in either direction. At some pressure (around 7 psi in the performance chart posted above) the motor can not pull the diaphragm in either direction and simply hums at the 60 cycle frequency with full pressure within the diaphragm chambers (diaphragm at each end of the shaft each with an inlet and outlet valve arrangement) and the shaft simply stays still in the middle. The pump "strokes out". Anyone familiar with a closed center hydraulic system it operates in a similar manner with the pump stroking out at the designed pressure. At this point the motor will be drawing the same electricity (I think, I'm no electrical engineer) but only maintaining maximum pressure with no flow.

The fact that there are no bearings and that the armature of the linear motor floats on air with the only friction involved being the flexing of the diaphragm and compression of air, they are very efficient at pumping air AT LOW PRESSURES. A conventional pump can't touch the efficiency. But as pressure increases where a conventional pump and motor maintains flow much better, the linear pump drops off drastically.

That is why, when used within their design capabilities, the linear compressor will pump a lot of air on little electricity. But efficiency rapidly drops off with pressure (depth).

Thank you for the input so far. I have my hands full with this pond. I bought this house and like a few other things the prior owner did, I think he may have skimped on some of the pond construction. I want to make it right.

As far as the depth goes, I'm not really sure where "full actually is" or really how to determine where the "full level" was intended to be. Maybe I should start a thread in a different part of the forum as I don't want to get off topic.

Long story short, this pond seems to lose a few inches of water a day. When I fill it up fully (seperate pump on a well) it is right at 10' as I measured it with a rod. However, the pond will drop probably a good 5' if I don't keep filling it (few hours per day).

The prior owner decided to plant 2 willow trees right on the bank of the pond, they grew to over 40' tall in 8 years they were there, I cut them down last week. I am sure they did not help with the water level and I am also sure the roots are still absorbing water.

I am going to start another thread in a different part of the forum about the problems I am having with the pond. I did want to start designing an aeration system, but I am thinking I have other issues I need to deal with first, lol. Thank you again for your help, love this place! Matt

re: the willows.

Call a local farm supply store, or a farm fertilizer supply store and ask if they have Tordon RTU (1 qt.). If they do, go buy it. Cut the stump of the willows again (if you can) to have "new" wood showing. Apply Tordon RTU to the complete cut area on the stump. That should stop it from re-growing. Just the cut stump, it doesn't do any good to apply it to the soil around the stump.

Without doing that, you'll be fighting willow shoots and sprouts for a long time.

Thanks esshup, I will do this first thing in the morning.

So I was fortunate to be talking to a good friend of mine, she said she just removed her aerator from her pond and wasn't going to be putting it back in. Long story short, I agreed to exchange some work for the pump. Wound up with a 1/4 gast pump setup (74r130) is the model number, 100' of weighted air line, and a 9" Kamair diffuser setup. I was looking forward to building my own, but the price was right on this one!

I want to have fish holdover throughout winter pond falls to be about 6' deep in winter, should I run 1 or 2 aerators to keep it open? Not sure what kind of fish yet, hopefully something for the dinner table occasionally. I live in Northeastern WI where it gets awful cold. Any advice?

One diffuser if it will hold up to the air that the compressor has, and place the diffuser 2' below the surface of the water.