I am having trouble lower my phosphates in my tank. it is reading at 1.0 and i use the red sea test kit. i do weekly 20 percent water changes with RO water as the replacement water. i dose kalkwasser and i also dose iodine and magnesium on occasion. i am now using phos-ban 150g of it and it hasen't really touched the phosphate level. it's only a 55gal. could the kalkwasser be reacting with something to produce PO4 or what else could be wrong i can't figure it out? oh i also use instant ocean salt.