I'm an officer with a local Lake Association. Our Impoundment (reservoir) has a long history of fish kills. At 6800+ acres and over 18 miles long it is impractical to aerate multiple areas so in 1981 a large system was installed to provide a refuge during periods of low DO. It was located in an area that was both convenient as well as being was a narrow passage that could easily be cobered. The area of the open water field is approx. 40 acres. Yes it is huge. There are 2 blowers each with a 40HP motor and a 775 CFM capable Cyclo blower. The picture below shows an aerial photo of the field in operation.


The system stands idle until February when it is started up based on demand. During the months of December and January a small system is operated to maintain an area of open water where the tubes enter. This system is what I am looking to address.

The standby aerator is a large tank piston compressor set to deliver air via an orifice. The cost of operation is on the order of $10 a day. In a typical year it will run around 60 days so that is $600 to do the job of a typical pond aerator. The motor is in need of repair which is understandable as it cycles far too often running 1.5 minutes every 5 minutes. At the very least the cycle rate needs to be addressed.

What I'm looking to propose is that this existing equipment be kept as backup, but look to add something that runs on the order of $30 a month versus $300. It needs to run reliably 24-7 approx. 1500hrs straight and truth be told does not need a diffuser. A simple orificed hole has sufficed for all these years and requires no maintenance.

I'm hoping some of our aeration experts can chime in here with suggestions.





For a little perspective from the edge of the visible ice area to the aeration field is 5.6 miles:

That is one big aeration system. Did it seem to help in reducing the amount of fish that were dying each winter?

I regards to your large tank compressor, do you have any idea how much air volume is needed and what the depth is where the bubbles are released?

Its funny how one mans simple can be another mans HOLY COW that's big! 'Cause to me... HOLY COW that's big!

I think he is referring to his stand by aerator as the simple one not the 40 acre 26 diffuser unit. I guess it is possible to aerate 40 acres. Sue Cruz of Vertex probably dreams of those styles of aeration systems.

Just looking for a simple system to protect the Point of Entry for the lines for the main aerator.

In the big picture there is a D.O. modeling study that is ongoing. I have some ideas that would incorporate something smaller located at key points that could operate on a similar scale.

The main system here runs for over $100 a day which realistically is too much $$$

Once we get the new "pond type" standby system operational and proof of concept we can look at other things like variable frequency drives for the big units and small point units.

What I know about the current standby system is that the motor is up for rebuild as it has a dead spot that it will not start from. The plan is to rebuild and keep it. What I have been told is that it runs at 50 psi and delivers air via a valve or restrictor. It runs approx. 1.5 minutes every 5 minutes which is far too often. At the very least it needs the pressure increased and a regulator added to drop the psi and flow so that the cycles are reduced.

So, if I understand this correctly, the small unit is just to keep the water open where the big units air lines enter the water?

If thats the case, then the water depth should be pretty shallow for the standby unit diffusers, and the only question would be how many points of entry are there? (that would determine the number of diffusers needed, which would allow us to calculate the CFM needed.)

For the smaller pond units, psi is based on (roughly) 0.5 psi for every foot of water that is above the diffuser.

You got it

Being a reservoir the head will vary as water level will fluctuate. Point of entry is a single point and realistically we just need to keep it open all winter. I don't know that it matters 10' or 30' hole. The lines are primed with calcium chloride to stand at the ready in fall then reprimed at startup.

I was thinking just a basic entry level vertex unit should suffice? We just need to push a steady volume of a handful of CFM through a couple of holes probably 3/8" diameter and depths less than 20' Since they are at varying depths and the water level varies if we can't quite push to the lowest one at full pool we should be able to get there once the water level drops and it becomes necessary


220v no problem.

It definitely does not need to do this:

I know of none bigger (main system) as this one has about 4 miles of 2" tubing as I recall. It was installed on the ice and cut in while the ice was over 18" thick.

The "field" was replumbed in 2009-2010 to the tune of around $50,000. This was using same blowers and motors etc.

As to fish kills after aerator installed this is a sticky subject. FERC controls the license as to how the waters are operated. There is a major study underway to model the reservoir and predict D.O. trends. We are hopeful that this will link the D.O. to water levels (volume) and that we will see a change in operations that carries more volume into winter gradually releasing as the winter goes on.

Yep, I think a PondLyfe system would work and save a huge amount of energy costs as it only uses a 1/4 hp 120v Brookwood compressor. They can operate diffusers at up to 30' water depth. I'm checking now to see if they are available in 220v flavor. I'll report back here when I find out.

Are there any components in the system that will be affected by the calcium cloride? What do the diffusers look like in the large system? And I thought a little over 2 miles of bottom line tubing was a lot for an aeration system.......

The unit will be located inside a building. It does not need to be a kit. In other words a 1/4-1/2HP Brookwood compressor may be all we need. 120v is also available.

The calcium is poured in the lines of the main system only. The main system does not have actual diffusers. It has 2 pair of 3/8" holes per line. Two midship and 2 at the end.

I can only assume that the standby system is the same.

P.S. The line is unweighted tubing with rebar strapped to it using both hose clamps and zip ties so there's nearly foot for foot of rebar to tubing.

I wish I could add some value to your solving your problem. That is definitely a grand scale and very cool project IMO!

Side Note: And I b*tch when I have to run an extra 100' of air line. 4 miles, 5280' = 1 mile; that's a lot of air line!!!

Hesperus, check your PM's.

I agree - 1/4 hp Brookwood compressor. If you add a membrane diffuser it will make the ice free opening larger (25-50ft) if needed. It should operate at about 5 hrs per each kw of electricity - 120V.

All laid out on the ice lashed to rebar then the ice was "trenched" and the line dropped in.

So here's the facts more or less:

Current standby system operates at $10 per day 60 days on average for cost of $600

1/4 HP 115v Brookwood would run same time period for $40

1/2 HP 230v Brookwood would run same time period for $68

The 1/2 HP unit would give me an extra margin of error in capability and still get me the lion's share of the cost savings, but the operating cost is about 70% higher. Then again $28 more cost is peanuts compared to the $500+ savings.

This is assuming the $10 per day estimate is correct.

Sounds like using a compressor that is not really specifically built for the job? A high pressure compressor doing low pressure work maybe?

One way to cut down the cycle frequency is to use a storage tank. Say for example a 500 or 1000 gallon propane tank. Then the compressor might run for ten or twenty minutes (up to cutout pressure), but stay off for an hour. Regulate the flow at the output of the storage tank. Same concept as a shop compressor. Larger tank means longer run time but fewer stops and starts. Same thing with water system that uses pressure tank. More storage == longer run time and less stopping and starting. Right now the volume in the lines is the only "storage" volume you have, thus the frequent cycling.

Normally an aeration pump runs all the time with the pump matched to the required cfm. Sounds like you got more pump than you need. Cutting the cycle time down would help out on the electric cost a bunch, not to mention less wear and tear on the motor and compressor.

Well folks the 1/2HP Brookwood is in! Thanks go to Scott at Hoosier Pond Pros for getting us a great deal on the unit. I was a bit nervous at first and we'll see what happens when temps start to really drop, but I think we could have easily gotten away with the 1/4 HP unit.

Temps have been mild as of late, but this is what we have after 3 days of operation staring with about 8" of ice. This is a no maintenance system with a simple set of drilled holes to discharge the air and no diffusers. In the foreground is where the main lines enter the water through poly culverts covered with crete for protection during spring ice out.

Wow!! Very interesting! If you start to have problems when the temps really start dropping you may want to pop some Air Stations on the ends of the lines....

I talked with Scott about trying different diffusers, but I'm just one representative of one of the stakeholders in the project. The no diffuser concept just churns and there's no risk of biofouling. Add to that, the system was under water all year. Below is a pic of what things look like beneath the surface. The main lines are on top and the 10' pipe underneath is what this system is discharging through. Kind of tough to pull up from underneath the 14 other lines/rebar on top...

Nice when a plan comes together. Sounds like will save a lot on electricity.

Thanks for the update. Let us know throughout the winter how well it works.

John, from the pictures, they have no idea how large the system is.

If anybody is just reading the thread from the bottom, start at the beginning of the thread. The size of the system is mind boggling.

IIRC, those lines going into the lake are each 2" dia, correct?

snrub, it'll save a whole lot on electricity over what they were using to keep that area ice free in the past.

I believe that the large lines are 2-1/4"

I figure a 1 season payoff of the small compressor, but the main system cost is still $6-9k for 60-90 days of operation.

For point of reference this is one of the two blowers. The blue tank to the right is the old standby system. A 60 gallon approx. horizontal.

I remember reading this thread quite a while back Esshup. I did glance back up through the pictures also. Yes, it is quite a system. I knew the small pump was just to keep the ice open in one small area.

That pump looks like a Roots style pump. It looks very similar in size to the unit we used to use to blow grain into a 100,000 bushel grain bin. They are high volume, relatively low pressure pumps. Still have the pump but now use a big auger to fill the bin instead. Now the pump sits in a shed. I think ours has a 20hp 3 phase motor driving it. We ran about 10 psi as I recall and if we got up to about 12 we were getting close to stopping up and cleaning corn out of pipes. A smaller 15,000 bushel surge/feeder bin fed it with a VRD motor on an auger. Often ran 24-7 when filling the bin.

Been a while since I read the thread all the way through, but as I recall that pump cycles on and off. That would seem a waste to me as electric motors (especially that size) take a lot of electricity to start up. Seems like a smaller pump/motor that run continuously would be better.

Not sure on what the RPM range of those style pumps are, but a larger pulley and slowing the pump down (with associated smaller motor) might be a possibility also. Seems like the CFM was not sized properly for the diffusers, although I'm sure on a system that size they were likely learning as they went along and probably did not want to undersize. Probably not a lot of previous experience to draw on.

Edit: Ok......I went back up and read the original post. Now I see where only the small system was the one that cycled on and off. So disregard most of what I said. That was the one that used a high pressure compressor where only a low pressure compressor was needed.