Algae help

[Mrv85]

I have a 75 gal, what used to be a reef tank with a 30 gal refugium. My ph got too high and I had some major losses. I did damage control by doing significant water changes. Everything is now stable. I have a small amount of the normal green algae.
I have a problem with this brown stringy algae. It forms air bubles and it clings to the rock and substrate mostly where the lights are strongest. I do small water changes regularly and clean when I do. It seems to be getting better or maybe it's wishful thinking.
What kind of algae is this and how is it best combatted?

[zebrafish]

It sounds like bubble alge. I had that for awhile. What type of water are you using for your water changes? RO/DI? I was using water that had to much phosphates in it and teh alge was feeding off of them like crazy. Once I switched over to RO water it went away.

[OnTheReef]

True bubble algea are rubbery. If you have brown stringy mats with air bubbles in them, they are probably dinoflagellates, which are feeding off the nutrients that were released when some of the organisms in your tank died and decayed. If you are doing high-powered nutrient export with a well-tuned protein skimmer, live refugium and consistent water changes, this will probably subside gradually, though I would siphon it away with the water changes.

[Ciarán]

Definitely not bubble algae IMHO!! Sounds remarkably like a cyanobacteria mat/film. It depends how old your tank is. Tanks naturally go through cycles of algae for the first year or so, going from diatoms to filamentous to cyano etc. etc. its not an exact science by any means - every tank has different variables that will promote certain algae and inhibit others - but there will be times where a specific type of algae growth is favourable, as the bacterial population of your tank begins to reach a stable equilibrium. Given your pH problems, it could have rendered the balance of your tank favourable for this dark brown/tan stringy mat algae, not strictly an alga at all but "cyanobacteria". Good feeders on cyano are: Mexican Turbo snails Turbo fluctuosa and trochus sp. snails.

f you have brown stringy mats with air bubbles in them, they are probably dinoflagellates

Also a possiblity, a way of getting rid of dinoflagellates is by SLOWLY raising your pH above 8.4 using a Kalk drip and apparently after a week or so the bloom will crash (Wilkens 1989). However, dinoflagellates tend to bloom almost spontaneously in epidemic proportions and cover EVERYTHING, sounds more like the rather less exotic cyano as i mentioned. A picture should em.. clear this up if you will excuse the pun!