Would it be a bad idea to set a heater at the lowest setting at 69deg F. just to maintain a constant temp. Right now temp can vary from 58- 66 deg f. There are a blugill, perch. and something that looks like a spekled trout. he was in with the sucker bait. The blugill still have a couple of worm like things attached to the pectoral fins. I did salt and methyl blue. It just turned them blue