If were are turning this thread into additive talk, a lot of "color" additives contain metals like zinc, copper, etc. that kill off some zoox to make things brighter instated of deeper/darker and also have more contrast. I have no idea what is in KZ products, just talking generally. Since there are not really well know set points for a lot of these metals, and also no great way to test them (no, ICP is not that great at it even though they give you a number), some could already be on the verge of harm before dosing while others are not. A lot of these metals are added slowly in food but often skimmed out, or bind up into rock/sand, so there is usually enough/some in tanks already and some tanks could be near the tipping point before a mass addition from a bottle. Again, ICP is really not good to test a lot of these things so no matter the number, you really have no idea what is going on. It is easy to see why additives with metals in them might work OK for one and be horrible for another.