If you don't have test kits or at least test strips you should get them: you should establish a benchmark set of parameters you want to hit, and test and correct until you get them. I grow corals: I use the Seifert Alkalinity, Seifert Calcium, and Seifert Magnesium test kits. I don't yet have a PH meter, but those three tests alone, plus a salinity tester and two thermometers (I run a backup), give me a pretty good picture of water quality. Running the test kits is futzy at first, but oh, so worth it. A skimmer is a very good investment. These all may be basics you know and have, but I recall you've been having troubles before now, and thought I'd provide as much info as I can on what works for me.