You just need to wait. It can take many months for corals to regain zoox that they expel during a heat event. Chasing this will not help anything further along.
Eventually, they will be fine again and although you can give credit to the "last thing" that you did, they would have come back on their own.
Stability and patience is what is needed here. If you want to get your big-three more towards NSW values, then this is always a good idea, but take your time and do it over a few weeks.
About Nitrate... you do not have zero or else nothing would grow. If you have algae on the glass, then you have plenty. Unless you do a IC/ICP test, then you will never know what it really is, so do not chase it if you have things growing in your tank.
Eventually, they will be fine again and although you can give credit to the "last thing" that you did, they would have come back on their own.
Stability and patience is what is needed here. If you want to get your big-three more towards NSW values, then this is always a good idea, but take your time and do it over a few weeks.
About Nitrate... you do not have zero or else nothing would grow. If you have algae on the glass, then you have plenty. Unless you do a IC/ICP test, then you will never know what it really is, so do not chase it if you have things growing in your tank.


