I was reminded today, of a lesson I learned several years ago. If you get a test result that's completely out of line with what you expected, repeat the test! I tested PO4 today and got a result of 0.23! It was only 0.17 two days before and I had dosed lanthium to reduce it. Rechecked it twice and got 0.13 both times. Years ago I over reacted to weirdly low alkalinity result. I over reacted and dosed to elevate my alkalinity to where it should have been. Unfortunately the next day my corals looked stressed and I eventually lost a couple. The alkalinity that day was sky high.
