Hello,\n\nI am a novice I have a 75 gallon tank that has been up for about four months. I am having a Cyano issue. For fish I currently have, 3 chromies, 3 fire fish, 1 scooter blenny, 1 diamond goby, 1 chocolate chip starfish, 1 sally lightfoot crab, and 1 clownfish. I went to my local fish place and my water results were as follows: Ammonia - .75, Nitrites - 0, PH - 7.4, Nitrates - 15, Phosphates - 0. I currently have a protein skimmer that is rated for a 110 gallon tank as a HOB as well as a filter with active charcoal and PVC substrate rated for a 110 gallon tank. I have two power heads, one in the back going down the length of the tank and one on the opposite side front corner pointed up. I am having an algae issue especially with Cyano and I need help. I have attached a pic of the current tank. Any assistance is greatly appreciated.\n\nThank you,\nDaniel C.