Millie tips bleaching
 

I have a couple Millie colonies that I thought were showing good growth tips but they are now to long to be new growth. I have been struggling to maintain my cal and KH as Ive added massive colonies lately. So I was thinking it was ALK burn but my test this morning were: CA-390 (was down to 340 earlier this week) KH-6.7 (it peaked at around 7.3)
My Phosphates, nitrates, ammonia is 0

Im running the full zeo system, doising zeobac, zeostart3, amino acids and coral vitalizer, and k-balance.

I should add I have great polyp extension on all my corals and even the bleached areas have polyp extension.

I did have cheato in my sump but it has been shrinking lately so I took it out last night. Nick (titus99) told me it could be leaching out as it dies off, so its out now as well.

Could it be bleaching from the lights ? Are you running carbon ?

Could be the lights I guess but they are all close to the bottom of my tank.
I was running carbon in a reactor but took it off line a couple days ago.

Some of my corals started bleaching as my water was like yours, too clean
They expelled their zoox, then the lights started burning them
I've since been overfeeding, and turned off half the lights, and some corals are starting to come back

what intensity are you running your mitras at?

If it were lighting, I would expect the entire colony to bleach, not just tips.

Have you tested k. It should be around 380. A overdose can look like alk burn on tips

The lights peak at about 80% on eco mode.

Yeah I would think that the entire colony would go if it were lighting too. I've also had some sps with tips that look like there bleaching, then end up transitioning to a different color.
Or maybe it's an alk burn

Nevermind just read you alk levels! I've never heard of potassium burns before. Might be worth a try to test for it