copper can react with certain nutes and ph levels letting copper break down into your res so it is not best to use but other things can replace it. We had a good chiller and how to session this summer when it was hot out.Lotta options.The chill probe thing your talking about wont really work as its for such small tanks and only drops a few degrees so youd need a few.Lookinto using mini fridges, window a/c units modified, water coolers you get drinking water from at work.Those can all help.Someone also just barred a long length of hose under ground outside his hose then covert ran it back into the basement and forced water via a pump through it as the cool ground cooled the circulating water by 15 degrees.