This is the best thread I have read. I am going back to using my diatom filter. I used it in freshwater a few times a year to clear up the tank, but was told it would be a disaster in a reef tank. Obviously not. I didn't measure anything, but salinity for 2.5 years, but I started again as my sps were browning and never did great. However, the real thing that puzzled me was that my cheato just disappeared in my refugium. I replaced it twice, then tested my parameters. I almost had a heart attack as my PO was 1 and my Nitrates were over 100. Oddly enough though, my frogspawn was growing like a weed. After I made some changes with flow and reduction of phosphates and putting my refugium on a swing timer vs. 24/7 and expanding the types over algae, things have been much better, but as things turn for the better my PO is at .2 not .02 and my Nitrates are at 60. I needed this thread to remind me that it is not about chasing numbers, but health of the inhabitants.