Help, I can't figure out what's wrong

hey guys, so I posted on here a week or so ago about my millepora that bleached. It completely died now. I have no idea why or what is going on in my tank. I have done nothing different since I started it. My montipora which was on a great road to recovery has now also bleached. My trumpets aren't fully expanding like they used to and my kenya tree has been closed for 3 days now and so have my GSP. I just did a 5 minute light iodine dip on the kenya just to see if maybe it could be a bacterial thing. I haven't seen and change yet but it's only been a few minutes so it's too early to tell. My newest acro is doing fine along with my maze brain, torch, zoas, ricordea, maxima clam and duncan. I checked all my levels yesterday afternoon.



Ammonia - 0

Nitrite - 0

Nitrate 0-5

Phosphate - 0

pH - 8.0-8.1

Temp - 77.5-78.5 controlled



Did a water change within the last 2 weeks so i know my mag, calc, alk are fine.



I have no idea what is going on! there are clearly no nutrient spikes, protein skimmer is removing a good amount of waste. The only thing I am slightly battling is a brown algae growth that is pretty persistent. It's not diatoms, I've had diatoms before. This stuff sticks to the surface of things. I have controlled it quite a bit and slowed its growth greatly with a turbo snail and frequent glass cleaning.



Is there anyone out there that knows what could be going on? I am losing too many corals for my liking without any obvious signs of why. Thanks in advance.