What to do?

[lpsreefer]

I use ro/di water. I feed 6 pellets a day. My light cycle is only 7 hours.
Im also using Rowa and carbon.
It has a biocube skimmer.
There's only two fish and a nem.
The tank was fine up to about 4 weeks ago.
It was right around the time one of my rics shrunk down and went lights out.
The tank has been running for over a year with no problem.
This problem has stumpped me.

I took out half the rocks and set up a 20 gallon with a heater, power head, filter(the sponge has been in my main system sump for a year I got five of them prep'd for when I need them), and an air stone.
17 gallon of water came from my main system and 3 is fresh saltwater.

I pulled off as much algae as I could and scrubbed it with a tooth brush.

I don't mind recycling the rock. All I know is three types of algae went sexual and over took the system in two days.