Has any one ever tried using shade cloth over ponds to keep the water temps down ? I have a 150 ft by 80 ft wide pond 14 ft deep I want to keep trout in all year long but the water temps get to high in summer. I was thinking of buying shade cloth that they put over top of greenhouses and suspending it over the top of my pond by about 6 ft to 8 ft to keep the water temps down during June thru August. I would also like to know if running my aerator which is at 6ft deep at night would help cool the pond water down. Any advice or experience would be appreciated.

Been there done that over part of a small 1/10th acre trout pond. Don't believe it did much but then again like I said it was only over part of rhe pond.

IMHO your aerator will not cool down your pond. Your best bet to cool a trout pond down and flush nitogenous waste is groundwater flow.

How much of the pond was covered and what was the light blocking percentage of the shade cloth

The pond is rectangular and the bottom sloped to facilitate draining. 90 feet long with the deep end 40 feet wide and the shallower end only about 25 feet. I had the shade cloth over the shallow end about 25 feet of the pond all the way across. Shade cloth was the densest I could purchase.

I don't think my partial covering was a good test of how well shade cloth would work. If I was to seriously do this I would place it over the entire pond and in that case I believe it would keep temps down a little.

It seems like I remember seeing in the past a link to a product that was for keeping ponds cool. It was floating balls that covered the surface. Am I remembering wrong?

I haven't seen that but I know of one hatchery that floated the high density 4 X 8 foam boards on their small flow through holding ponds in the summer. Perhaps once could float them around the shoreline where the water is shallowest? If I did it I would run the yellow rope you get at the hardware store over the top of it in a couple of places with the ends staked on shore to keep the wind from pulling it up or moving it around.

Unfortunately the high density foam board is no longer cheap brand new. I have heard of people getting good deals on it at building surplus stores though.

I don't need any measures taken as 45 gpm of well water flowing into my 1/10th acre trout pond 24/7 in the summer with steep sides keeps temps pretty low in the hottest part of the summer. Once I put a pier in and was able to measure the temp of the water column I was amazed at how low it was. Upper 90's air temp and water temp was in the low 60's the top few inches. Down from there to the bottom was right around 60.

I'm thinking the top would have been warmer but colder below that if I didn't run the diffuser at night. However I believe running the diffuser part time was imperative to prevent an anoxic layer from developing near the bottom. OTOH I really don't know as to what effect the incoming well water has and could prevent that.

It would be interesting to experiment with different approaches without jeopardizing the fish as in no diffuser running but well water, or running the aerated well water straight to the bottom vs. spilling it out on the surface.

Unfortunately with about 500 lbs. of trout upon harvest in the fall after a two year period I can't take the chance at fish that are worth as much as they are.

I am getting prices on 3 different types of shade cloth. White at 50 % shade, black at 80 % shade and aluminized at 80%. The salesman told me he had a customer use the aluminized and had over a 10 deg. drop in his greenhouse. I only intend to cover 2/3s of the surface and have it suspended 6 to 8 ft above the water. I just need to find out how hard my wallet will be hit with the 3 different types. I only have a small spring feeding my pond and when we have a drought it quits flowing. My pond used to leak down to 10 ft deep but I had that fixed when I drained it and covered up a gravel seam that the original excavator guy left open with straight wall sides. This other guy who sloped my banks said my idea would not work and my pond was leaking else where, but I proved him wrong after I had him do what I wanted.
I also wanted to get a fountain aerator to run at night when temps are cool as I know this will help cool the water. There a company that makes these water cannons for swimming pools to cool the water down when it gets too hot by about 10 deg. and they are run at night, but they want over 3k for those things. Well I guess I will give this a try as long as it is not too expensive.

think trout - Did you ever follow through on your shade idea? I looked at this idea briefly, but it was too expensive for the area I was considering.

I did find that some of the cloth manufacturers do have specials on leftovers and "seconds" that were much cheaper. I think the seconds were instances where the cloth got a few folds going onto the roller. Not good enough for a country club pool, but great for a pond.

Good luck on your trout.

Think Trout, I'd put the diffuser at the deepest point and run from about 1am till 5am to keep the bottom oxygenated, and warm the bottom as little as possible. Much will depend on how many times a day your aeration can turn over the pond.

Keeping the diffuser at 6' is okay for keeping water open in winter, but lets the deeper, cooler water below the diffuser go anoxic during warm months. If there is a thermocline, the trout won't be able to survive in the deep water in summer, no matter the temp.

A few years ago I found out by accident that running my diffuser 24/7 was not a problem as warming of the trout pond was insignificant. Found out because I forgot to shut if off at night a few days in some really hot water.

Keep in mind my trout pond is quite small (1/10th acre), very steep sided and received 51.6 F. well water at ~ 45 gpm 24/7.