Algae and Death, a mystery

[Mark_C]

I've got a few small, but thickening areas of green hair algae over the past month.
Its growing slowly, densely, and surely.
I had bryopsis in the past and took an aggressive stance against it (see below) so I'm surprised to see the GHA outbreak.

I've also had the loss of a very well established torch coral over the past few weeks, though other LPS doing well, and haven't seen my spotted mandarin 2 weeks whom I'm assuming lost.

I feed small amount of live food 1x day (no waste) and a small amount of home-made frozen food 1x per day.
My lighting is on a 8 hour full cycle with a 3 hour ramp at either end.
The tank is 90g with a 10-15g water change done twice a week.
A BRS reactor runs GFO mixed with carbon.
There's a bag of Chempure Elite in the sump.
I have Dragons's Breath macro growing slowly in the fuge and Chaeto growing very slowly, if at all.
Tried to make it all bulletproof against bryopsis resurgence.

Currently my API kit (I use it as a quick general scan) shows phosphate 0.
My Red Sea kit shows phosphate 0.
My Hannah shows phosphate 0.01.
Nitrates are effectively 0.
Nitrites are effectively 0.
Ammonia is 0.
My pH is 8.4 (via Red Seas, don't trust my Hannah chems atm).
The temp constant and controlled, as always, through Reefkeeper with backups.

Primary Question - How the &*^% is the GHA propagating?
Secondary - Could the loss of the torch and the mandarin be related to the GHA propagation?

Any experience, insight, or thoughts appreciated.

 

[horseplay]

Maybe your tank is still new and going thru every algae species like mine did. From my planted tank days I learned algae come because of chemical imbalance and may or may not due to the nutrient levels. (there is actually a method to overdose nutrients to prevent algae growth in planted world.)

I had GHA bad at one point. Covering pretty much all rock surfaces. It's very green and tough and can not be removed by brushing. The good news is getting a couple of Emerald crabs and the algae will be gone in no time. These guys are much better algae eaters than any tang. After a few months algae was gone from both of my tanks and I can't grow them even if I want to (and I do want to). Now I have go to the beach to collect algae covered rocks.