Keeping Fish from overheating

i always have some plastic bottles filled with water in the freezer. so when the power goes out or if our air conditioning is not working, i can float the ice filled bottles in the tanks and that keeps the temp from getting too high.
i watch the temp gauge on the tank closely though. down here in FL we do get some bad storms this time of year that knock out our power. and the temp in the house can get well over 100 degrees.
i also did this when one of my tank's heaters was screwed up and wouldnt turn off and the temp of the water was almost 86 degrees. i removed the heater and floated an ice filled bottle in the tank. it gradually brought down the temp. it's better than adding ice cold water to the tank, that might shock the fish.

I typed up an article today. Hopefuly some mod will approve it soon.

How warm are your tanks getting? Here in FL, we get days that are 90-100+ pretty frequently over the course of six months and haven't had any problems. I don't think you need to start putting ice in the tanks as the temperature fluctuation will be more stressful on your fish than a higher than normal temperature. I would add something to cause surface agitation to allow heat to exchange more effeciently, which should keep your tanks a little cooler.
If it makes you feel any better, local fish farmers *may* put shade cloth over their ponds in the dog-days of summer, but there are a lot of growers that don't even go that far...

I think you would really have to go crazy with the ice to get a big fluctuation. I put a quart size block in my 29 gallon every other day or so and it will only lower the temperature about three degrees. Ice packs, the plastic ones you buy for coolers, do a better job than straight ice or frozen bottles of water.

You could spend a load of money and get a chhiller, but I also use the ice method in the summer and it worked for me. I'm pretty sure they prefer the water being cooled other than sitting in high temps.