Oh, ok...
I wouldn't touch them with the toothbrush or similar yet.
Try to deal with the algae controlling your water parameters.
The extreme can be treated with hydrogen peroxide dips, but you should avoid the treatment and try to deal with the water chemistry first.
If you dip or use the brush on the zoas without making sure the chemistry is taken care of, the algae will come back!
Good luck!
Grandis.
What he is saying is that the gfo is kinda like a band-aid it might fix ur phosphate problem but the underlying causes why its there in the first place are still there. Make sence? But i wouldent say to stop using it just try to figure out why u need to use it.
Just because of the GFO presence in the system.
Like I've said before, if some had problems with SPS bleaching...
Many people have problems with zoas and GFO could be the case many times.
It's what GFO is suppose to do, besides binding phosphates.
It also binds organics, precipitates CaCO2 and therefore can cause biological effects, like stress, tissue recession and bleaching.
The "fast" loss of alkalinity and the binding of organics is what I believe should be the main reasons to quit the use of GFO in reef tanks.
Grandis.