Is this Diatoms?
 

My tank has a wall to wall outbreak of this. Not sure if it's lighting or water> Params seem all OK. Well Sg, Ca, Mg, Ak was really high tho. Just did a W/C

Help please, Blew as much as I can off the rocks but it's everywhere and my Zoa's are all receeding and mostly dissapeared.

Need a picture to help you, but if it's brown and can blow off like dust, yes I would say diatoms. Diatoms are caused by the silicates in your tank and will go away once they are used up. I found blowing it off daily and every other day water Change like 5-10% cleared it up quick.

Sorry pic was too big had to resize
Ya it blows off mostly with a power head. Looks stringy like kinda tho

http://banditpowdercoat.com/Powderga.../IMG_17961.jpg

If it's stringy probably dinoflagellates. Same strategy to clean it up. Water changes and nutrient control.

I'm not an expert maybe someone else can chime in but to me looks like GHA covered in diatoms. Only as that's what my tank looked like at the beginning. Once my diatoms left I was left with GHA.

I don't think hair algae will blow off, +1 on dinos.

I do have a GHA issue too, but mostly at the upper levels of the tank, like overflow rim

Ya, looks like I can see some in the lower part of the pic, are you using anything for phosphates?

Only using Biopellets

Pellets not real good at po4, might need some GFO.