Pond Boss Forums AERATION Systems questions Big pond aeration

I just discovered this site two hours ago. I live on a 13 acre lake in Tiffin Ohio. To me this is a large pond rather than a little lake. We want to get rid of organic sediment that varies from one foot deep to more than six feet deep and the water varies from two feet to seven feet. Is there anyone out there with a large pond that has a system installed and working to their satisfaction?

Dale- Welcome to Pond Boss. I'm sure you will enjoy the topics and become obsessed with checking the site everyday.

Personally I have over 15 years experince designing systems for lakes your size. As for seeing how they work in person, Ted Lea with Cleanponds in Waynesfield,OH has two very well maintained demonstration ponds to show you all the diffusers and systems available.

I'm sure it would be worth your drive to his location if you would like to proceed with aeration. He is on this forum and should be cheking in soon.

Thanks Cary. We have already visited with Ted and were very favorably impressed. He has quoted a system and so has Clean-Flo who use ceramic diffusers. Our committee is uncertain which is better-ceramic or flexible or perhaps either will work. We are new to aeration and have a lot to learn.

Dale Foltz

The ceramic diffusers were great in their time. The problem with clogging due to calcium deposits make them more labor intensive to maintain than the flexible membrane diffusers. Secondly, the ceramics if you plan on using a rotray vane compressor, tend to clog from the inside as well from the carbon dust created by the compressor.

Flexible membrane is the way of the present and future. If you have any questions I would be happy to help you as well.

I'd try the ceramic stones if I had a way of changing them periodically. I've got both and I still say the ceramic are much better. I've only changed my ceramic ones once in 6 years and then they didn't need it. I push the same flow through both of them and while it does require 4 ceramic stones to get the same back pressure as my single membrane my observation is that the ceramic ones move 4 times as much water. I've convinced myself that aeration is almost totally dependent on how much water is moved, not how many CFM are pumped. They are related but for a given CFM more water is moved by finer bubbles. The 4 stones cost about the same as one rubber one. More water moving means you are getting much better aeration for the air you are pumping and thus more for your money. Theoretically you could get by with a smaller pump for the same job. Over many years I would think you will see a big difference in sediment reduction with the better movement of water. I understand why many Pros recommend the rubber ones for low maintenance. And they are used exclusively in places like treatment plants for that reason. If you rig things up so the diffuser unit can easily be pulled up for mainenance all you need to do is screw on some clean diffusers. My plan was to try the ceramic ones and replace with rubber if they didn't work. I started out with two sets. Each time I pull it up I remove the old ones and replace with clean ones. Then I clean the old ones for use next time. I haven't had to put my old ones back yet. Got 3 years on current set. I monitor air pressure and when it begins to rise I'll swap the stones out. Of course this depends on your water so if you try this be prepared to change later.

bz- good comments. As stated, the stones were state-of-the-art when they came out. Unfortunately, the stones have only a 3mm hole thereby a 3mm bubble is released.

With today's membranes, they are punched as small as 0.5mm. and as you correctly stated, there is more surface area with smaller bubbles.

I beleive Vertex has measured the stone set ups both 4 and 6 stone and the numbers were less than their membrane disc.

The clogging is directly related to how hard your water is. It sounds as you have an ideal condition where your stones are not clogging quickly. You are lucky. I have had to change stones as quickly as three weeks in some lakes and up to 2-years in others.

The problem with cleaning the stones with acid is first you are dealing with acid. Secondly, these stones are made by baking silica sand in a temperature of 1200 degrees. The acid eventuly causes the sand particles to release thereby increasing the size of the hole where the bubble is released.

I think your option of starting with the stones and switching to a membrane could be an option for Dale. But if it were my personal pond, I would opt. for the new membrane diffusers due to both proven performance and reduced manintenance concerns. I would rather be fishing than maintaing the pond.

One of the problems in starting with stones if they are sized correctly is that you have an enormous amount of hp/ cfm that you will not need when switching to flexable membranes.The last data I reviewed concerning stones (glass bonded silica)were the rates off of the Aquatic Eco Systems website 2-28-02 and they listed the SL9 system which is a 1 HP rotary vane (approx 12 cfm) with 4 plates of 6 stones each,the circulation rate was listed as 8,000 gallon per minute per /HP The Otterbine AirFlow X3 system published at the same time was 11250 gpm per hp and the Vertex Air 6 was 21060 gpm per hp.When I spoke to AES a few years ago about the 4 stone setup (per plate)which is the ALA4GL I was told the circulation rate at 1 cfm in 12 ft of water was 1250 gpm while some rubber membrane diffusers were lifting just under 3000 gpm, (2778) to be exact.Cary is correct as the pores get bigger in these stones the bubbles are larger and the lifting capacity is lessened. So they can wear out and you dont necessarily see a pressure rise or drop.Larger pores which would mean less pressure can be offset by other pore space that is being plugged. A glass bonded stone or a ceramic disc will and can lift as much water as a flexable rubber membrane "IF" you put 2-3 times as much CFM/hp to them.One of the displays we have set up is a Koender 7 inch round Airstone in 12 ft of water along with the AES ALA4GL and a Vertex CoActive AirStation and an ATI AirPod2 The lifting rates at 1 cfm range from 500 gpm to 3000gpm and when the air supply is switched to each one you can not tell the difference between 500 gpm and 3000 gpm. point being lots of bubbles still come out of diffusers that are not lifting much. One last point, it is the lifting ability of the diffuser to expose the bottom water (verticle current)to the atmosphere that aerates the water column, This is where turnover and sizing comes into play.Circulation is the most important specification for increasing dissolved oxygen levels and improving water quality in general.

Great points Ted.

One statistic I left out was CleanFlo,and their ceramic disc, they state (as of today on the Clean Flo web site) a circulation rate of 8000GPM per HP in 6 ft of water.This was an impressive calculation in the 70's as thats when that inhouse test was done. "Times Change"(they also offer an option to a rubber membrane diffuser)

Thank you all. I will download all this info and take it to our committee meeting tonite. Now that I know about this site I will keep everyone up to date on our progress. I have personal preferences but will wait until committee meeting is over to respond to the above remarks.

Dale Foltz

Our meeting is over and we are confused about turnover rates. One quote uses one turnover per day and the other says 2.7 turnovers per day. There must be some guide lines. If muck reduction is the goal and we have potential to remove three or four feet from some areas, would more diffusers and higher turnover do a better job? Can anyone calculate the muck reduction rate vs turnover rate? Once we feel comfortable with flow rate then we can have each vendor quote on systems with similar performance. After that we can then evaluate which diffuser is best for us relative to maintenance costs and service life.

Dale Foltz

That's what I was looking for, some numbers. I did buy my setup back in 2000 at which time I was using the AES data as a guideline. At that time I could not find a membrane that would make bubbles as small or move as much water as the stones. If membrane diffusers are now better I need to check them out again. I bought the best membrane I could find at the time and as I said above it doesn't move anywhere near the water as my ALA4GL stones with equivalent CFM. I'll check out the membranes Ted mentions, maybe I'll switch! I will say that the membrane I do have has never required maintenance.