Should diffuser be in the deepest part of the pond

Hi there

New 1/2 acre pond is starting to fill and I’m researching aeration. I’m looking at a Gast pump and bottom aeration via a diffuser. My question is should I place this diffuser in the deepest part of my pond? I’ve attached some photos which shows my pond. The back of the pond where there is water is around 12’ but there’s a hole that was carved out that gets about 14’.

https://ibb.co/gW7RZgY
https://ibb.co/Mg8rWZS
https://ibb.co/xJgcDBK

My question would be would I be OK dropping the diffuser in that deep hole to maximize my turnover ? Or should I put it somewhere in the center around 10-12’? Also would there be benefit to me adding a second diffuser somewhere?

Thanks!

Are you putting structure in for the forage base?

I'm not experienced with aeration, but from what I've read here, you would not want the diffusers at the very bottom of the pond, or even close to the bottom (deepest part of the pond) during the winter as you could be super-cooling the water if the air temps are below freezing. In the winter, you may only want the diffusers to keep an open hole in the potential ice.

In the summer, you get benefits by keeping a diffuser near the bottom (deepest part of the pond)..

At any rate, let's see what others say.

What Gast pump are you looking at getting? My 0523 (1/4 HP) likes to run 3 diffusers nicely. I think 2 would work well, but one may not be enough to handle all the air flow the pump can put out. I know the Vertex diffusers can take 2 plus CFM per head, but they are rated at 1 CFM (EDIT: 1 CFM for the liftrate flows), so that is where I run mine.

What diffusers are you going to use?

A 1/2 acre pond is around 1 million gallons and you want to turn that water over in a 24 hour period, or less. A single Vertex diffuser would do that in as little as 6' of water (almost double at 12'), but a 1/4 hp Gast pump would be trying to push 3CFM or more through it. It would be better to run 2 diffusers, or 3 ideally (given the 0523 pump).

Consider putting a diffuser in an 11-12' depth near the 14" hole and a second one midway between the first diffuser and the next farthest bank. This helps cover the whole pond and reduces the stress on the diffuser membrane. I am speaking theoretically with regards to stressing the diffuser. I have accidentally pushed 3 CFM through a single diffuser for a short period and I know it can take it, but I tend to error on the safer side and shoot for 1 to 2 CFM per diffuser for long term use. I say to not put one in the 14" hole just in case the hole could act as a cool water refuge below the thermocline. Some folks manage this in larger ponds for heat relief during a hot summer. After looking at you photos...it dawned on me that you may be using this pond for swimming and not necessarily fish. If that is the case...I would drop a dual diffuser into the deepest part and size the pump for that number of diffusers and depth.

Given a bit larger budget for some additional weighted tubing, fittings, and an additional diffuser...add a third one to the pond. A pump of similar in size and design could easily turn your pond over in a 24 hour period and leave room to only run part of the day (or night).

Post your pump and diffuser choices and we can get into some of the calculations that I have generalized above.

You will want to place diffusers in 2 places, one in the deepest part of the pond for use when the water temp is above 50 degrees, and one in approximately 3'-4' of water for use all year long, or at the very minimum when there is ice on the pond. Running the diffuser in the deepest part of the pond during the winter will cool the whole pond to near 32 degrees, and that will stress the fish.

You will have to have either a manifold at the edge of the pond to direct air to one or both diffusers, or run two lines to the pond from the compressor and have a manifold at the compressor.

You should adjust the number of diffusers per AirStation so that you don't run too many CFM through them. The Vertex diffusers are rated at 4 CFM MAX per diffuser membrane.

Originally Posted by esshup

You will want to place diffusers in 2 places, one in the deepest part of the pond for use when the water temp is above 50 degrees, and one in approximately 3'-4' of water for use all year long, or at the very minimum when there is ice on the pond. Running the diffuser in the deepest part of the pond during the winter will cool the whole pond to near 32 degrees, and that will stress the fish.

You will have to have either a manifold at the edge of the pond to direct air to one or both diffusers, or run two lines to the pond from the compressor and have a manifold at the compressor.

+1 Well said.

Originally Posted by Quarter Acre

What Gast pump are you looking at getting? My 0523 (1/4 HP) likes to run 3 diffusers nicely. I think 2 would work well, but one may not be enough to handle all the air flow the pump can put out. I know the Vertex diffusers can take 2 plus CFM per head, but they are rated at 1 CFM (EDIT: 1 CFM for the liftrate flows), so that is where I run mine.

What diffusers are you going to use?

A 1/2 acre pond is around 1 million gallons and you want to turn that water over in a 24 hour period, or less. A single Vertex diffuser would do that in as little as 6' of water (almost double at 12'), but a 1/4 hp Gast pump would be trying to push 3CFM or more through it. It would be better to run 2 diffusers, or 3 ideally (given the 0523 pump).

Consider putting a diffuser in an 11-12' depth near the 14" hole and a second one midway between the first diffuser and the next farthest bank. This helps cover the whole pond and reduces the stress on the diffuser membrane. I am speaking theoretically with regards to stressing the diffuser. I have accidentally pushed 3 CFM through a single diffuser for a short period and I know it can take it, but I tend to error on the safer side and shoot for 1 to 2 CFM per diffuser for long term use. I say to not put one in the 14" hole just in case the hole could act as a cool water refuge below the thermocline. Some folks manage this in larger ponds for heat relief during a hot summer. After looking at you photos...it dawned on me that you may be using this pond for swimming and not necessarily fish. If that is the case...I would drop a dual diffuser into the deepest part and size the pump for that number of diffusers and depth.

Given a bit larger budget for some additional weighted tubing, fittings, and an additional diffuser...add a third one to the pond. A pump of similar in size and design could easily turn your pond over in a 24 hour period and leave room to only run part of the day (or night).

Post your pump and diffuser choices and we can get into some of the calculations that I have generalized above.

I was looking at the GAST 0523 like you referenced here https://www.septicsolutions.com/sep...523-rotary-vane-pond-aeration-compressor

I was also looking at the dual membrane diffuser here https://www.septicsolutions.com/sep...rane-diffuser-assembly-for-pond-aerators

But now after seeing some comments I wonder if I would be better served buying 2 independent diffusers like shown here https://www.septicsolutions.com/sep...rane-diffuser-assembly-for-pond-aerators

I definitely want to use this pond for fishing... it's going to be a swimming/fishing pond until my wife decides swimming in it is no longer fun

So the question remains then.. if it is a good idea to run 2 diffusers, should I put one in the 14' hole and one midway from the next farthest bank, or put the deeper one in closer to 12'?

Also, am I picking out the right pump and diffusers for the job? I really appreciate all the guidance here!

Originally Posted by Sunil

Are you putting structure in for the forage base?

I'm not experienced with aeration, but from what I've read here, you would not want the diffusers at the very bottom of the pond, or even close to the bottom (deepest part of the pond) during the winter as you could be super-cooling the water if the air temps are below freezing. In the winter, you may only want the diffusers to keep an open hole in the potential ice.

In the summer, you get benefits by keeping a diffuser near the bottom (deepest part of the pond)..

At any rate, let's see what others say.

Yes, the plan is to place xmas trees and some brush along the deep side bank, as well as several rock piles. I'm also planning on adding a diy structure near the deepest hole.

Use the dual membrane for the shallow water, winter AirStation, use the single membrane for the deep water AirStation. Run both during the summer as the single membrane one is not rated to handle the CFM from the compressor.

Like I said before, you will have to build a manifold to direct air to the 2 different AirStations.

Originally Posted by esshup

Use the dual membrane for the shallow water, winter AirStation, use the single membrane for the deep water AirStation. Run both during the summer as the single membrane one is not rated to handle the CFM from the compressor.

Like I said before, you will have to build a manifold to direct air to the 2 different AirStations.

Thanks! Do you have any preference on the diffuser style ? I noticed these two styles have significant different prices

https://www.septicsolutions.com/sep...rane-diffuser-manifold-for-pond-aerators

https://www.septicsolutions.com/sep...rane-diffuser-assembly-for-pond-aerators

Membrane diffusers are very popular. Check out Vertex and Matala brands too. Esshup sells the Vertex ones on his website. See his signature above. And, many people here like their Gast pumps.

With the 0523 and 3 diffusers, placement is not too critical since you are moving plenty of water. Esshup has been at this for some time now and his advice will have its advantages.

Originally Posted by esshup

Use the dual membrane for the shallow water, winter AirStation, use the single membrane for the deep water AirStation. Run both during the summer as the single membrane one is not rated to handle the CFM from the compressor.

Like I said before, you will have to build a manifold to direct air to the 2 different AirStations.

Esshup I appreciate your advice! I was a bit lost and you've got me on the right track... I didn't even realize Hoosier was your store.. I've been eyeballing your hybrid crappie as I'm not too far of a drive away.

Originally Posted by Quarter Acre

Membrane diffusers are very popular. Check out Vertex and Matala brands too. Esshup sells the Vertex ones on his website. See his signature above. And, many people here like their Gast pumps.

With the 0523 and 3 diffusers, placement is not too critical since you are moving plenty of water. Esshup has been at this for some time now and his advice will have its advantages.

I'm going to have to think through this.. I appreciate all this input! My pond tends to get deep pretty quickly so there aren't a whole lot of great spots for a shallow diffuser so I'll put my thinking cap on for aesthetic purposes as well. Sounds like I'll really be moving some water around though which is great!