What is a safe water temp? I live in the south and it gets pretty hot. My pond get alot of morning sun and it can warm up pretty quick. What are some ways to keep it cool? It was 90 degrees yesterday so my pond was 75 to 80 ....that is with putting a board over it to block the sun...Remember I have bad city water so I can't add cool water to cool it down...

Fish that like cooler water like goldfish and koi tend to start suffering above 80 degrees F but can take 85 degrees F for a while. By suffering, I am referring mostly to the lower oxygen levels in warmer water. You can counter some of that would good aeration. Just buy an aquarium air pump if you don't need a large aerator. That plus the normal filtration will help. Higher temperatures may also make fish more listless, and they'll eat less (sounds like me in the 85 degree F heat here; I'm not very heat tolerant!).

Shade is the best way to lower the temperatures. Shade is best from plants but can be made with umbrellas (you can even just stick up a beach umbrella for a temporary shaded area), pergolas, or even a board over part of the pond. Be sure there is still plenty of space for gas exchange and to let the heat out at night. You might want to elevate any covering so it's not actually sitting on and covering the pond but above it at least a few inches to let the heat out.