Removing GHA causing SPS bleaching

[Gonzo Reefing]

at first I thought it was unrelated, but for the third time I have moved GHA via slowly scrubbing rocks and holding a siphon next to the brush. Inevitably some loose GHA churns in the tank but i catch most of the non microscopic portions while the rest get caught in the filter socks.

Why is this causing otherwise colorful corals to bleach? Polyp extension seems unaffected and zoas and LPS also don't seem bothered. Matter of fact, some across dont seem phased but others turn nearly completely white. Now I'm paranoid to continue fighting the battle against GHA.

I have tested nutrients before the cleaning and again about a week after each time and there are no swings. No3 at about 5 ppm, and PO4 at .01-.03.

Any help on how to avoid the corals stressing out while continuing to battle GHA would be appreciated.

 

[Ludders]

have you got any pics? How long have you had a GHA problem and is it definitely GHA and not bryopsis?

 

[Gonzo Reefing]

have you got any pics? How long have you had a GHA problem and is it definitely GHA and not bryopsis?

I've had the GHA for about 3 months or so. Its definitely not bryopsis. No structure to the algae at all. The filament is the same throughout (no thicker branching parts etc.) and very thin. Not home so no pic right now, but the affected corals look like themselves in every way except that they're very pale, almost white. While other SPS look unphased.

 

[Dan_P]

at first I thought it was unrelated, but for the third time I have moved GHA via slowly scrubbing rocks and holding a siphon next to the brush. Inevitably some loose GHA churns in the tank but i catch most of the non microscopic portions while the rest get caught in the filter socks.

Why is this causing otherwise colorful corals to bleach? Polyp extension seems unaffected and zoas and LPS also don't seem bothered. Matter of fact, some across dont seem phased but others turn nearly completely white. Now I'm paranoid to continue fighting the battle against GHA.

I have tested nutrients before the cleaning and again about a week after each time and there are no swings. No3 at about 5 ppm, and PO4 at .01-.03.

Any help on how to avoid the corals stressing out while continuing to battle GHA would be appreciated.

Just thinking out loud...

When algae are damaged, they can leak their innards, cytoplasm, and this is a great bacterial food. Some coral are sensitive to carbohydrates which algae can release. The bad reaction might be caused by increased bacteria growth from what the algae releases. You might me unlucky in having coral that are sensitive.

This is the first time I heard GHA removal associated with coral distress. Might the GHA also be harboring dinoflagellates or cyanobacteria?

 

[Gonzo Reefing]

Some parts had minor cyano. Definitely no dinos. I've had dinos before and this was nothing like it anywhere in the tank.