Green hairy algea for 3 months now

[razingkane]

I've got a 30 gallon reef tank that's been going for 3 years now. I've never had any problems with the tank up until about 3 months ago. Now I'm drowning in green hairy algae.

Temp is fine and I've cut the lights down to 8 hours. I'm doing 10% water changes with RO/DI water every week with water I've been buying from the same store for 3 years.

PH 8.2
Amonia 0
Nitrite 0
Nitrate 0
Salinity 1.022
I've been using phosgaurd.

I've got 3 fish. At last count the cleaning crew is around 8 hermit crabs, 2 pep shrimp, and snails. It's mostly a soft coral, and leathers tank.

I try and suck out as much algae as possible when changing the water. I've been taking the rocks out and gently brushing the green algae off with a extra soft tooth brush. Some of my rocks are covered with so much green algae that I've had to resort to tossing them out.

It's getting to the point were I'm getting sick of the tank. What am I missing here?