Jack makes an excellent point here. I set my upgrade tank up almost a year ago and while I had great success keeping sps in my 40g I have had nothing but struggles over the last 10 months in keeping them in the new tank. I have gone thru 2 sps crashes in my tank and I now believe it was because I starved them by shooting for low nutrient levels and too much light. We are always trying to tweak the tanks and get a little more in color and growth. I have stopped trying to get low po4 numbers and have let my levels rise to around .06. A lot of the sps that I thought I had lost with the crash I left in the tank and most are starting to show signs of tissue regeneration and the ones that did survive have amazing color and pe.
There are a few very succesful threads on here where the members havent tested for po4 in a few years and let their eyes do the testing and this is what all of my rambling is about. If the tank looks good, the corals look healthy, there's no nussance algae growing then let it be. I am not saying to ignore testing as you should still conduct regular testing but dont try to over tinker with the tank. One thing I have learned in this hobby is....it doesnt take much effort to make a tank take a turn for the worse but it takes a lot of effort to get it back. Just my .02