TOO MANY FRAGS, blocking flow you need to get rid of some. Its so strange low Phos and low Nitrate. Try siphoning the substrate on that side, I bet you find it has a large build up and Cyano just loves it. I am stating to think it is more of an Enzyme imbalance. First herd that from Chemipure I wonder if Chemiclean is nothing more then the Enzymes you put in Septic systems. I believe that is how it works when added to your Aquarium is it attacks any sludge, waste, food build up in and on the Substrate and on the rocks and all the nooks and crannies. I believe that is why many say there water after has never been so clear and would make sense why you need to make sure there is lots of O2 . Anyhow it would makes sense as your power head is moving the water to that side and as it does is driving the waste and food and stuff into the bed and lodging it under the rocks. Give it a quick siphon and see what comes out.
