View Full Version : High phosphate and 0 TDS

08/09/2017, 04:57 PM
I've had the 4-stage BRS RO/DI unit 150GPD for about 2-years now.

I've been battling GHA and wonder if my media and membranes are ready for replacement. I'm getting zero on the out TDS meter but my phosphate are at 0.12 ppm with 2 ppm Nitrate. If the membrane was shot could I get a high phosphate reading while showing 0 on the TDS meter?

My feeding schedule is light so I don't think it's from over feeding.

I did order new media and membranes today from BRS so we'll see if that makes a difference. But I'm curious about the relationship between phosphates and TDS.

08/09/2017, 06:43 PM
Using a Hanna Phosphate Checker (not ULR model), phospate was detected in my RO/DI water when the TDS went above zero.

08/09/2017, 06:54 PM
I'd try a phosphate test rated for fresh water use to see what might be in the RO/DI. I suspect that the source for the phosphate is elsewhere, but anything is possible, and checking the output should be inexpensive. Many phosphate kits will work on fresh water. What are you using currently?

08/10/2017, 02:47 PM
I'm using the Hanna Phosphate ULR checker. I looked on their site and can't tell if it'll work on fresh water. Anyone know?

08/11/2017, 08:39 PM
No, that won't work. At least, it's not rated for that. Most other kits are.