Who Gives A Fish Forums

Mate, if your sponge filter's new, it might just need more time. My 10-gallon took a full month to cycle, even with bacteria starters. Patience is key, innit?

Quarantine's a must. I learned that the hard way. Lost half my stock once because I got lazy. How's your tap water's chlorine levels? Some cities use chloramine now, which doesn't gas off like chlorine.

Yeah, RO's the way to go. I run mine through a peat filter first to soften it up. Also, keep an eye on your KH, 'cause if it drops too low, your pH might crash. How often you planning water changes? With Discus, I do 30% twice a week.