Let's see, I do use a baster to blow of rocks that may catch detritus or leftover food. I don't stir up the sand BC my huge narssius snails and my fighting conch really stir up the sand a lot!! The only chemicals that I have put in, BC I was just getting started chemically with corals, was stuff to raise the alkalinity, which was really low and now is at 9, my calcium stays at 450, and magnesium which I just tested was only 300!! So I started a very slow drip of only about 5 teaspoons which equals only 25 grams which will only raise it about 100 mg to 400 which is still very low but haven't had any problems and its the most I can put in for one day the bottle says!! But I will slowly raise it to the level it should be at! I have a reef octo 100 HOB that skims like a boss!! And I just tested my phosphates and they are 0-0.01
I would retest the magnesium, 300 is probably a false reading.