i don't have a phosphate test. i am using trace elements/kent calcium right now. I am waiting on my reef solutions to get here (internet order). how do you mean, "same fish food"? if you mean same food everyday, no... i mix it up with frozen brine, formula 1, sometimes flake, freeze dried mysis shrimp, seaweed salad, and garlic pellets. i feed a different food everyother day.