I have a pond thats nearly a little over an acre. The average deph is 10' with the deepest being 13ft. It is Spring fed from 3 diff locations and the pond holds 1,200,000 gallons. I have about 110 rainbow trout stocked in this pond. Here is the problem.

I have 2 kasco aerators running 24 hours now as i did the gradual startup even though its a new pond just to be safe. Initially the diffusers were at the deepest point 13ft and 10ft.
SOMEHOW they have moved to 12' and 6'.

Anyways i took the surface temp today and it read 80 deg. I put an orvis thermometer on a line and cast it into the deepest part and when i retrieved it after 10 minutes it read 78 degrees then i put a float on the line and cast it out at the 8ft mark and read the same. I did have one floater last week and one this week. If those temps are correct how are these trout even living or is my thermometer messed up? I guess what i need to ask is am i running the aerators to much that its mixing to much warm surface water? Should i just aerate at night? And also should i put the aerators back to their original positions at 13' and 10' ? At this point i fully expect to loose all these trout Any help would be greatly appreciated

How old is this pond? New ponds generally don't need aeration, and it is likely that moving all of that water around has made the pond relatively uniform in temperature and at the temps you posted I agree that the trout won't likely live long. BTW, I am no expert, and hope the real ones chime in soon.

I did see that you say it is a new pond.

Yes about 9 months old, i dont know if i should shut the system down now and try to get the bottom cooler or not ?

I'd shut the system down for at least 4 days, and then run the aeration from the deepest points for 4 hours from about 4am to 8 am for a week, then check temps. If you have or want to spend the $$$ on an O2 meter, knowing your dissolved oxygen at the deepest would be very useful info!

My guess is that your water quality is really good, and there is plenty of dissolved oxygen if your water temps are that high or your Rainbows wouldn't be alive. 70* is considered the deadly high temp zone, but in good conditions, they can survive in 80* temps, but not for very long.

What is the temp and flow from the feeder springs? The trout probably hang out close to those if there is significant flow and lower temps....

Are you seeing the rainbows? Are they feeding? Did you take the temperatures where the springs are flowing into the pond? If the springs are not inflowing a significant amount of water and if you are not seeing the trout they could be dead lying on the bottom.

They were feeding last night although i didnt feed much in these conditions, the one spring the overflow from our springhouse enters at 57 degrees but it only provides 2 gallons a minute, Didnt check the other spots, i fear that what you say may be true Bill. So at this point should i just let it run??? i seen one or two near the surface so who knows

Rainman wont shutting this down for that amount of time hurt the o2 levels to lethal if it hasnt already happened???

Bob, what else is there, aside from the 100 trout? Being a new pond, and considering the large volume of water, low amount of detritus, oxygen consumption, and DO reduction, should be minimal.

I've had trout alive in a clients pond with 78 degree water temps. 3 bottom diffusers and a large surface agitator had O2 levels at saturation.

I've had trout in my pond die at mid 70 degree water temps.

My pond is 18' deep.

One year I bought a low temp t-stat and only ran the bottom diffusion aeration system when ambient temps were below 70°F at night. Didn't do a durn thing, in fact the trout died even quicker because the pond was within a few degrees water temp too to bottom, and the O2 levels weren't high enough for the trout. In other words, aerating only at night did nothing.

Next year I didn't aerate at all, and the pond set up a thermocline. The trout lived a month longer than the previous year, but they still all died around July 4th.

I would move the diffusers to 1/2 the max depth of the pond, and run them 24/7 and hope that you keep your O2 levels up enough for the trout to survive.

Now I look at trout as October thru mid June fish.

The trout are the only thing we have in the pond.

Wow interesting post esshup, i have read countless post in the archives about direct o2 and water temp, trying to find the perfect balance etc etc and what i come to learn is that sometimes for as much as we know we know nothing.

The O2 mortality threshold for trout is 5 mg/L.

Are you sure you are correct on your math for the gallons of water? Im getting 2.5 -3 million gallons with 27k gallons per inch.

Good point, I saw the numbers but didn't pay much attention to them.

One acre foot of water is 325,851 gallons. If the pond is one surface acre, and it averages 10' deep, then it's over 3 million gallons.

I was told last year to look at my rocks and see if there is bubbles forming on their surface. There was all kinds and 24/7 aeration was way to much.

Running the aeration 24/7 in the summer warm saturated the pond more than just running it at night. I now run the air from 1am to 7am only when it is cooler. It has kept our pond cooler over all and the pond is new as well. We only have perch in our pond.

It is neat swimming. The top 4 feet is warm but your toes are about 10 degrees cooler.

Cheers Don.

My brook trout pond usually stops going out the overflow and begins to drop around August/September for a while then flows again. It's been so dry here it's already down a foot. I have a spring with good cold flow about 1,500 feet away. I'm running 1" line from it to the Brookie pond. Will check the temp at the source and the temp coming out at the pond. I will run the line mostly through heavily shaded woods but I still expect a rise in temp. If it's excessive I plan to get the backhoe out and dig a couple deep holes in a mostly eastward facing low spot uphill from the ponds and loop a few hundred feet of line and bury it in the hole before continuing the run to the pond. This should cool the water sufficiently prior to allowing it to fall about three feet as it enters the pond to help with oxygen. The vertical drop from the spring source to the pond I estimate to be about seventy feet, perhaps a bit more. This pond is quite small, about 1/10th acre. Not sure if you have a layout that might allow you to try something similar but thought I would put this here for consideration. I plan to have this in place over the next couple days. Ran 600 feet after work this evening.