Solid! I got your chat, glad to help. That’s so much cycled rock you simply don’t need to test for ammonia using any meter ever again on it, you’re done cycling.
it works like this:
have you ever seen your LFS, or any peer on any reef board run an oxygen test on their tank? I’ve been online in reef forums 21 yrs straight and only seen it once, in a focused chemistry forum study here.
nobody tests for oxygen, it’s a gimme
it works itself out fine in reefing
ammonia in a display is just like that, for the reasons stated prior.
simply stop testing for ammonia permanently. It cannot rise all of a sudden, to kill your fish. Old cycling science thought it could, but we’ve advanced, it can’t.
if you continue to test for ammonia on this tank, expect fear, dread and doubt at each interval.