Jim, I fought with the hair algae for about 2 years in the past. I have tried various herbivores from snails & crabs to fish & sea hares. I tried various chemicals. I tried periods of lights off, elevated magnesium, you name it! They either didn't make a difference, had directly a negative effect (for example, the algae fix chemicals had little effect on GHA but it knocked out my chaeto), or had only a temporarily positive effect followed by a negative effect (specially when livestock such as the sea hare died in the tank).
In the end, what worked for me, was to let the algae do its way until it finished the nutrients in the tank. So, I made sure the system & maintenance is good:
- good RO/DI water
- aggressive skimming
- longer lighting cycle for sump, although at that time my chaeto was overtaken by algae. But by having the algae growing faster in the sump, it competed with the one from DT
- phosphate reducing media. I ended up using bio-pellets because the lower maintenance, but a lot of folks had very good results with GFO as well
- regular WCs
- control the feeding
- control the livestock, stopped adding CUC & reduced the number of fish. I was down to about ~10 snails, ~20 crabs, 2 shrimps and 5 fish in my 125G.
- manual removal of the algae + scrubbing of the rocks
- good flow inside DT and through the sump
When the algae finally receded it even surprised me - around that time I was contemplating to throw in the towel and shut down the tank. Once I noticed that it doesn't grow as much, I continued the manual removal & then fish+CUC were finally slowly able to contain it. My livestock of snails, crabs, couple tangs and dwarf angels seemed not to like GHA unless it was very short or very soft/dying.
My last step in the fight with GHA was to scrub GHA from the sump & fuge, then refill the fuge with clean chaeto. Now chaeto grows again in my fuge.
It's been more than 3 years since my tank is algae "free". Since then I saw a few specks around one coral that is slowly recovering. I never saw them growing to more than that.
From the earlier posts in the thread, I see you pretty much doing the same maintenance as I enumerated above. IMO, that's the right way to get rid of GHA. The reef keeping article posted by
@Judah001 is also very good & makes similar points. Continue on this path, let the algae consume the excess nutrients from your tank and you'll succeed in get rid of it. It takes time though, arm yourself with plenty of patience.
I literally took all my rock out, scrubbed it down and doused it in H2O2. Thought it was gone for good. A month later is was back with a vengeance
