Pocilopora is bleaching from base towards tips

[Koty]

After a long time found my alkalinity to climb from 7-8 to 10.9. A quick look at the tank revealed that my Pocilopora, my largest fast growing coral is bleaching. Parameters are fine rest of the corals are not showing any stress. Is it a missing trace element? (Did not harvest. my Cheato for a long time and I let algae grow wild on the front glass as I was not at home). Otherwise a cumulating substance which may be solved by GAC.

 

[cdemoss01]

#fishmedic
Noticed this wasn't in the correct forum category so I will tag the doctors here.

 

[CHSUB]

Most bleaching events in the ocean are from elevated nutrients weakening corals and a second stressor pushes the coral to expel zooxanthella. How is the flow in the aquarium? Could be growth is affecting water movement in the center?

 

[Justfebreezeit]

Agreed flow might be an issue getting to the middle of the colony

 

[Staghorn]

You’re the only one that can really answer this, but the fact that your alkalinity was off, you say you didn’t harvest your chaeto for a long time, and the algae on the front glass was way overgrown seems like symptoms of neglect. Trust me I know what it’s like because this has happened to me before I’ve lost tanks that we’re doing phenomenally just because I got busy and put it off for later and before you know it weeks or months go bye. Has mentioned above I would make sure your flow is good but also make sure everything is on point and give the tank some TLC. Good luck

 

[Koty]

Well I will admit that I am naturally lazy but this time I have a good excuse : I was away from the house because of the war with Iran my house doesn’t have a shelter and my daughter and my grandchildren who live in the north of Israel, less than 2 miles from the Lebanese border needed our help and so I could only watch the tank from cams and my neighbor, a sweet ninth grader fed my fish. I will work on the flow. I have one gyre that decline with time if you don’t clean it thoroughly I will get to that and update. My nitrate is less than 10 andmy phosphate. is .38. So it’s not so bad I may add a reactor with carbon to clean in case there is a specific pollutant. I will update.
Thanks!

 

[Koty]

Update: cleaned the wave makers added a TLF reactor full of GAC with 300 lit/h. Next week I will add another to start stripping the tank from phosphate. Substrate is saturated so it will never near zero. I got a 5 kg bucket of GFO….
The purple Pocilopora keeps bleaching while 30cm away there is a frag that grows like crazy:

Close up on the dying/bleaching zones: