Pond Boss Forums AERATION Systems questions Best compressor

The short story is I've decided on two plates (probably Vertex or best comparable value) at 12-15' of depth. What's the best compressor for this application? Links to any known deals would be greatly appreciated! Would be interested in rebuilt models as well. The only ones I've found so far have been very expensive $400-600.

I know I need ~4cfm, but what about PSI? If I'm splitting the line to run two diffusers, do I need twice as much PSI? To supply 10PSI to each line I'd need 20PSI total?

Full stats:
~1/2acre
average depth is probably ~10'
can house the compressor in nearby garage and run 50' to pond, split and run a 50' and a 100' line into the pond
location is CT
goal is to reduce muck, and maybe provide some algae control in order to improve swimming aesthetics (bigger fish would be a fun side benefit but isn't the goal)

I am thinking Vertex or similar high quality diffuser because getting most bang for my electricity is important to me. My understanding is running two of these should give me like 12 turnovers in a day if my math is right. 2000gpm * 2 * minutes in a day = 6M gallons per day turnover, my pond is probably less than half a million gallons.

current compressors I'm looking at:
https://www.amazon.com/dp/B07C8KQRWB/?co...lv_ov_lig_dp_it=undefined&th=1

https://www.wholesalesepticsupply.c...tKF4jd_9lS2E9h6uLne67UEM0_waAiMyEALw_wcB

My AFS THOMAS COMPRESSOR runs continuously without issue since installation on 5/9/2017. I clean the air filter regularly, just ordered my first maintenance kit (less than $80), and consider this the best bang for the buck following two failed rocking-piston installs. I am running at 240 volts with two FlowMax Ulta Series diffusers for a 3/4 acre pond with an average depth of 5 feet.

Based on information gleaned from this forum, I have changed my operating hours from 11:00 pm to 1:00 pm to avoid increasing the water temperature of the pond during the hottest part of the day. I still get some algae and unwanted plant growth, but it is manageable with the new operating schedule.

I like the Gast 0523 Rotary Vane Air Pump based on it's flawless operation and the ease of maintenance compared to the rocking-piston compressors.

I will be paying close attention to this thread as I am looking to buy 2- 1/2 hp pumps for my system. Please impart your knowledge upon an aerator noobie. I'll be tuning in.

Dean

Sorry I googled AFS Thomas Compressor but it brought up a few models. What model is this and how much does it usually cost?

Also is the GAST 0523 10 PSI enough to run two diffusers each at a depth of 15'? $500 seems a little steep to me but that's the lowest I see the GAST 0523.

The Gast 0523 can adequately operate up to five 9" membrane diffusers at 15'. I do it - sometimes 4 sometimes 5 diffusers. At 15' deep the pump should operate at close to 8psi sometimes less during low water conditions. Put a good quality liquid filled 30psi gauge on the compressor manifold. Pressure relief valve is mechanical insurance if operating it especially during winter. The 0523 rotary is a WORKHORSE if kept cool and dry. Cool meaning to not let it overheat as in not operating it in an air tight cabinet nor box - provide ample natural or air motor air flow.

0523 is very easy to rebuild and install new vanes and make minor pump repairs if rust forms in the vane cavity (change internal air filters, O rings, and end caps) . I have original 0523 units operating in ponds 15 to 20 years some longer before the first rebuild is necessary although these units do not run 24/7 mainly 4 - 8 hrs per day May through October in ponds 0.2 to 0.7 ac. Gast engineers tell me the motor bearings are 'rated' to last for 3 rebuilds. This unit in ponds less than 1 acre with the proper diffuser assembly in CT (northern US) would only need to operate 2-5 hrs per day for creating a daily pond turnover depending on pond shape and conditions. 20+ yr use at $400 equates to $20/yr - a very good investment. Take care of the pump and it will take care of you; ignore it and it gets costly.

I do not have a Gast compressor but it sounds like a lot of people on this forum do have them and it appears they are very functional. I am just going to answer your pressure question specifically. The pressure you need from the pump is a function of pressure losses in the line, pressure loss across the diffuser and the hydrostatic pressure (head) of the water. The pressures are additive for the line loss and loss across the diffuser. For the line loss it doesn't matter how many sections you have it just matters the total length of line. The loss across the diffuser is pretty small. Unless you are running a lot of line - 200' isn't that much - the biggest pressure to overcome is the head or column of water on top of the diffuser. That pressure is not additive you only need to overcome the head of the deepest diffuser. The common assumption is the water pressure is 0.5 psi/ft - that is an overestimation but it provides wiggle room and makes the math easy and is a good number to use. If you have a diffuser at 15' and one at 10' then the max head is 15 X 0.5 = 7.5 psi. The diffuser at 10' is not going to provide any additional head - it isn't additive. The manufacturer can tell you the pressure loss across the diffusers and there are charts that can tell you how much pressure you lose in the line. The line pressure loss is a function of the diameter of the line. The bigger the line the lower the pressure loss and therefore less required pump discharge pressure. Most people use 5/8" or 3/4" hose. There are some folks on here who are much better at estimating line loss than I am.

None of this is meant to make this a complicated problem I just wanted to answer your question with some detail in the event it might useful to you or others. One last note, when estimating pressures always round up. Unless you are on a super tight budget, oversizing a pump is always better than undersizing. If you are on a tight budget, undersizing will ultimately cost you more money. All the calculations aside, line losses are estimates and your pressure is going change based on conditions. My aeration system has run as high as 7 psi but normally runs about 5.5 psi.

Good luck!

Thanks Bill. I assume it's possible to put the pump on a timer? As long as it has reasonable energy efficiency maybe this is the easiest longest lasting option, although I'd certainly go for a slightly weaker pump and run it longer if it cost less. I'm also seeing Thomas 2660 pumps come up, how are those?

If the Thomas pumps are not a rotary vane design, they won't last as long as the Gast 0523. IIRC the 0523 is rated at 20,000 hours before needing a vane change.

Heat is the biggest enemy of the compressor, suck the air out of the enclosure and have the air that enters the enclosure blow across the compressor. It's like the old Mr. Goodwrench commercials. Pay me now or pay me later. Pay up front for quality stuff and you won't have to spend your time and money rebuilding it in a few years.

The Thomas 2660 is a 1/2HP pump. The Gast 0523 is a 1/4HP pump. Pretty sure it'll cost more each month to run the 2660.

I use the Gast 0523 in my 1/4 acre pond with 3 diffusers and a timer. The timer was bought from Menards (Model Number: 59733SE) and is one of those for outdoor use even though it is inside my pump house. The important thing is that it can handle the inrush current of the pump. A cheapee that is used for a single lamp or your Christmas tree probably won't last long, if at all. It says it controls up to 1/2 HP. I tested the 0523 for amp draw and it never exceeded 23 amps at start-up. The timer and pump has operated flawlessly for almost 3 years now.

One thing to consider is the flow (or CFM's) at your predicted pump pressure. Strictly speaking, the Lift Rate charts for the Vertex 9" single diffusers were generated at 1 CFM per head. I take this to mean that the diffusers operate best at that flow. I know one head will handle much more without self destructing as I accidentally turned my system on with just one head turned on. It was for a very short time and it did not burst. BUT, back to "strickly speaking" ... I believe in balancing the system to supply about 1 CFM to each Vertex head. If your system operates around 6 psi, which would be about right, the Gast 0523 should be producing 4 CFM. That's more than the manufacture's recommendation by double. This could reduce it's life and/or reduce it's water lift capabilities...



If it were my system (& using the 0523 and Vertex diffusers), I would consider adding another diffuser to it to help get the heads closer to 1 CFM. Having 4 would be about perfect depending on the line size and such. I only used 3 in mine to stay closer to budget and hopefully 1.33 CFM isn't too bad on the diffuser diaphragms or lift rate.

Matala on the other hand states..."The Matala Membrane Diffuser works with any air pump with a minimum air flow of 1.4 CFM and a maximum air flow of 4.2 CFM."

Sue Cruz from Vertex Water Features has stated here...

https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=31352

that..."The max is around 1.25 per disc. Most other membrane discs have larger slits requiring more cfm."

I hope this helps!