....I know my tap water has arsenic (but so do apple seeds right?) in it an manganese and lots of iron (might be good for plants). Guy at LFS said he metals are easy to get out. The salts in the Prime must dissolve them. So I have not use tap water before just bottled spring water. Should i just give it a try do you think the arsenic will kill the fish? I was going to set up the 10g get it cycled then either get the dwarf puffers if available or a betta. Or try it with some $0.10 feeder fish then let the puffers eat them ....just kidding.