I usually mixed my own fresh water through RO DI filter i have. and then i use that fresh water to mix my own saltwater. It had been good until i see all of my corals died from time to time. Until to day, i check my PPM on my fresh water. It showed me that PPM is 48 ( red ). Is it dangerous, right? My RO DI filter kinda turning to yellow. i got that one kinda cheap. should i buy a better one ? here is the link http://cgi.ebay.com/8-Stage-RO-Reve...ryZ20684QQssPageNameZWDVWQQrdZ1QQcmdZViewItem ....IS this one good? thanks for your time, guyz.