I have about 260 watts in my p tank, it is a 55g. I noticed lots of green algea growing on the glass now. Also the gravel looks like it is turning brown or black. I feed my p's worms and have live plants. Is this to be expected?
What I have found that worked for me in the past to rid the algae is decreasing the photo period and doing more frequent water changes.
I usually run my lights at 12 hrs/day. In a span of four days I decreased the lighting by 1 hr each day, ending with an 8hr photo period. Doing so will lesson the shock in time decrease on your live plants. I increased water changes to 20% per day. Something else you can try is using treated water. Sometimes algae feeds on certain nutrients in your tap. The contraptions that treat the water remove the excess nutrients.
One think I have learned mainly from reefing with lighting and algae is, no matter how much lighting you have algae wont be excessive if there isnt a nutrient source for it to feed on. Phosphate and Nitrate are algaes favorite "food" reduce levels of this and no matter how much light you have algae will be more controllable
I have 500 watt on my 54G reef with minimal algae growth