Levels fluctuating

[Cujo#31]

I am by far and away no expert, however I have run a 500 gallon system and if that has taught me anything it's that huge volume system perams are a lot like stopping a fully loaded freighter.........it's a long and painful process. If I were a gambling man I would hedge my bets on testing. I would also stash the salifert kits for back up testing Alk and PO4 and run Hanna. I keep test kits of each on hand just in case as a back up test to check reagent and the likes if I get odd readings, but unless you have a veritable forest of SPS your perams should not swing that badly. Calcium and Mag won't swing too terribly far unless you have the forest of SPS either.
That and you would benefit immensely from a reactor with a system that big. Good luck