I' still trying to figure out how an under ground (geothermal) cooling system is inefficient? Cut hole in concrete floor, dig hole, insert copper coil, back fill and patch concrete.
Na hose clamps are your freind.that right there eliminates the worry of a flood.if you can afford a chiller do it.care free chilling. If you cant afford one,frozen bottles it is.either way insulation of the buckets and rez will save you time/money.
I don't mean to interrupt the important pissing matches and dick-measuring contests happening here (do these threads have ANY mods?), but to get back to the OP's question:
OP, read through this pool shock thread. It will 100% work for you at 82 degrees. I run my cloners at 82 and have never had issues as long as pool shock is in there.
https://www.icmag.com/ic/showthread.php?t=219683
To summarize:
1. 1 gram of Pool Shock goes into 1 gallon of water to make a stock solution.
2. This stock solution is then added to the res at 6 ml/gallon every 3-5 days.
I've been using pool shock for years in my ezcloner couldn't have been successful without it. Never tried them on plants further in veg or in a nutrient solution but could be a good idea.