Do a Triton icp oes test, just search the internet for it. Also read up on the Triton method and you'll probably find that buying in to that method will cost you no more if not less then all the other additives and water changes you are doing now. I would include the tests as part of your monthly costs to start then later on you can spread them out to every 2 to 3 months once you find stability in your results from month to month. BRS has started a couple videos on it you can watch also and Triton has several guides on their method and they are all worth a read.