Quote Originally Posted by SimonB
Hi!
Nice looking build!
I did a quick check from the values given in your excel and it seems that the greatest deviation between air and water is maximum ~6°C at any given point (i had to translate to Celsius to get a better grip...).
What kind of humidity are you looking at during this period? I was thinking that maybe the system is working kind of like a cooling tower at the moment? It would be interesting to correlate these values to the wet bulb temperature.
It might be possible to utilize this to keep the temperature even lower in the system, but unfortunately optimizing for cooling will probably give an increased evaporation loss in the system and also increase the rate of buildup of unwanted stuff in the water.

But for a hot climate it might be an idea to give some other properties to the return flow to maximize cooling?

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.