Hi all, I have a DSB about 600 x 250 and about 20cm deep. I have course sea sand in the bottom 3/4 and a finer sea sand on the top 1/4. Water flows over at about 25mm over the bed and feeds back with an Eheim compact 3000 pump. Is this the correct manner? Do i have enough flow? Should I perhaps add another 3000l return pump to increase circulation rate over the DSB. My reason for asking. My tank is now 4 months old. I do waters changes every 4 to 6 weeks, and I seem to have a major algae problem. Today I had the water tested and found Calcium lacking, phosphates ok. Bought some Calcium additives and added bicarb to my return RO unit. I want to get rid of the green. Is this going to take forever, can I hurry it along? Please help!!!