your problem is the fluval and the skimmer, up grade the skimmer and get your self a sump in teh mean time a goby lawnmower blenny will clean it up but also how long as the tank been running live stock in the tank and also are you running a rodi systen, lights you have on the system.
Ok buy a algie blenny or hence lawnmower blenny and that should do the trick also try this veration for the lighting atinic-10k-atinic-10k try that and also have a different ver. of bulbs as well, might be your bulbs that are bad if they have black ring on the ends of them then it is time to buy new bulbs for t-5 users I would suggest going with wave point, or gelsim? < please corrrect me if I am spelling wrong.