Help! Green slime starting in an established tank

[gobble]

I've had my tank running for about 3 years now and never had an algae problem. A couple weeks ago I extended my lighting by an hour and also added two new pieces of live rock. I had some corals bleach so I dropped the light back down to what it's been for the last 2 years.

I've started to notice some green algae on the 3 years old rock. It can easily be pulled off but is starting to expand within the tank.

What should I do? Should dose something like Chemiclean?

 

[Flippers4pups]

What’s your water parameters?

 

[gobble]

alk 8.0
calcium 410
magnesium 1140
nitrate .5
phosphate .08

 

[Rpc07]

Following along I’m dealing with the same issue.