Wild Green Discus Pair Breathing Very Rapidly

[Paul Sabucchi]

If as he said at the start NH3 and NO2 are at 0 while having 5-10 mg/l of NO3 the tank seems pretty much cycled to me, I agree that with wild caught fish you have less leeway when resolving an issue so best keep checking those water parameters just in case

[Megalodon]

It's R/O Water, so I'm hoping not. Can R/O water have Chlorine?

Yes, I found out the hard way. It's actually kind of challenging to remove chlorine (especially chloramine) with RO/DI. I had to expand my system from one stage of generic carbon to five stages of specialized chloramine catalytic carbon. I would test the water after the 4th carbon stage periodically.

A lot of chlorine tests are for pools and not low range tests. Free chlorine tests won't even work with chloramine. It's been written that chronic exposure to as little as 0.003 mg/L may be enough to harm fish. The minimum detection level of colorimetric tests is 0.02 mg/L so even then you're guessing a bit.