How does GHA kill corals?

[Steve1500]

My colony corals are hanging in there but my frags (variety of LPS) are getting hammered by GHA. My water parameters are stabilizing (CA: 420, pH: 8.1; Alk 8.5-9; SG: 1.026ish, temp: 79F., and I finally got my phosphate stable around .05 ppm and nitrates around 5 ppm. Of course this has contributed to my GHA. But, how does GHA kill corals? Does it outcompete? Suffocate?

Is it the chicken or the egg.....does the coral die due to inadequate water parameters and then get covered by GHA or does the GHA kill first?

BTW, after a few months of battling GHA, I am giving Vibrant a shot. I have only dosed twice so time will tell. Still need to get a hold of the root problem though.

 

[Victoria M]

My colony corals are hanging in there but my frags (variety of LPS) are getting hammered by GHA. My water parameters are stabilizing (CA: 420, pH: 8.1; Alk 8.5-9; SG: 1.026ish, temp: 79F., and I finally got my phosphate stable around .05 ppm and nitrates around 5 ppm. Of course this has contributed to my GHA. But, how does GHA kill corals? Does it outcompete? Suffocate?

Is it the chicken or the egg.....does the coral die due to inadequate water parameters and then get covered by GHA or does the GHA kill first?

BTW, after a few months of battling GHA, I am giving Vibrant a shot. I have only dosed twice so time will tell. Still need to get a hold of the root problem though.

hi Steve, You are on the right track. Understanding water chemistry plays a role in algae problems is a big part of the war. Posting actual parameters is very helpful too. Algae grows over dead coral skeletons because they have a nice rough surface to grow on, also dying tissue give the right nutrients to feed the algae and last but not least algae can be offensive too by chemical warfare. Running some carbon intermittently can help remove those chemicals. Some folks have reported good results with Vibrant. There are a couple threads about it. check out the subforum on nuisance algae. good luck!

 

[lapin]

If its real bad it covers the coral blocking out light (nutrients).
The chemistry is a bit complicated.
Algae exudates are allelopathic to corals, mostly on the detrimental side.
http://www.pnas.org/content/108/43/17726