Down to one fish

[NaH2O]

Neither is ideal, IMO. Your water quality will depend on what is in it . Do you by chance have a TDS meter? (What is TDS?) For reeftanks, RO/DI is best to use. I linked you to an article in my last post on reverse osmosis....Give it a read. Here is another article, but it deals with tap water: Tap Water in Reef Aquaria

 

[Penny]

Wow, I'm surprised the poor little guy has lasted this long! Thanks so much for all your help!