| Re: Testing Water Help with Understanding Numbers well i dont know anything about the conversion,but 0 to 10 ppm means 10 ppm is what the fish can tolerate not meaning they are happy in their.i shout for around .5 ppm or less to have happy fish.un happy fish can easaly catch ich.2nd thing that is kinda high temp. most fish like th 78 to 81 range.if it gets too hot u will kook ure fish...and i dont see why u couldnt use it for a fuge |