Not BS. It’s a time bomb. Happened to me. Lost a Sherman and a gbta. Two of the rbta just staring to recover color after 2 mos of being dark.
Chemical warfare doesn’t happen all the time. But it only take one to release their enzymes or whatever when they feel a little bit too crowded. It starts a chain effect with other nems in the tank and even those that aren’t really threatened in general release shit.
And if you don’t have carbon running fresh then it gets to toxic amounts.