View Full Version : Strange Noise

04/02/2017, 07:18 AM
Any idea what this strange noise is? I've tried removing and reseating the RO Membrane. It's a new-ish 99% efficient membrane from Marine Depot, all filters are new, and the TDS is up on the DI input from 3ppm to 7. Any suggestions?



04/02/2017, 02:06 PM
I've never heard that noise before. The pressure gauge isn't flexing, so I doubt it's pressure fluctuations.

What is the TDS of the tap water and the TDS of the RO water (before the DI)?

Scott at SpectraPure

04/02/2017, 03:36 PM
The TDS of the tap water is around 450, it's silly high. I haven the sediment filter, a 5 micron then a 1 micron carbon block, then DI. The input to the DI fluctuated between 5-7. It was 3 when I started using the new membrane. The old membrane, which was original from Soectrapure, was 14 or so.

04/02/2017, 09:11 PM
450 IN/3 OUT is 99.3%. 450 IN/6 OUT is 98.6%.

The manufacturer's test conditions use 250 TDS and 5:1 waste:product ratio.

Higher TDS and/or a lower ratio will affect the rejection.

Your tap water requires at least a 4:1 ratio to help keep the membrane clean.

Scott at SpectraPure

04/02/2017, 09:14 PM
Also, I'm not sure of the history of the DI cart, but it was becoming exhausted when it no longer read 000.