Originally Posted by SimonB
I actually had a "temporary" green house over the system this winter. It really helped with stabilizing the water temps. Humidity (>80%?) was actually quite high. There was condensation on the inside of the plastic film most days.
As to the summer, I had a tarp wrapped around the sides of the system to shade it from the sun. That also helped to keep it cool.
Humidity is usually above 90% most of the time between May and October. The gold fish thrived in the warm water. I didn't get the blue gill until October, so they didn't see the worst of it. This year, I will be insulating a new fish tank with 2" rigid foam. Hopefully, that will help the fish. But in all of this, remember that my grow bed is acting like a radiator. Air temps warmer than the tank water will heat the water up. But when the air is cooler, the water will tend to cool off. That's why I'm trying to fit shade cloth into the budget.