Quote:
Originally Posted by
lilclowns 
Is is a dangerous level? I don't have a reef tank
Ah, sorry you posted this in the reef section so I assumed it was a reef tank, my bad. 20 PPM isn't bad for a fowlr tank, lower is always better but not always attainable. I would say "comfortable for your fish" would be no higher than 40ppm though I have seen fish live fine in higher I wouldn't subject my animals to it. I know 100PPM can be extremely toxic to marine fishes.