what size sediment filter for RO/DI

salty joe · May 10, 2018

I'm not sure what size sediment filter to get. I see 5 micron, 1 micron, 10um, just not sure.
I have municipal water and am changing RO membrane, carbon, DI resin and sediment filter because suddenly my treated water is showing 5 TDS. Anyway, any help with the sediment filter would be much appreciated.

miPapareef · May 11, 2018

BRS has a video explaining the trade offs of different size filters. I personally use the 1 micro because I have high water pressure and don’t have to change it too often.

LCC · May 11, 2018

I agree with miPapareef, get the 1 micron. If you were on well water instead of city i would recommend running a 5 micron then the 1 micron.

DesertReefT4r · May 11, 2018

1 micron sediment, 1 micron carbon, Spectrapure Dow or Filmtec RO membrane, DI. Each filter protects the one that comes next in line so having qaulity filters makes all the difference. Here is the setup I prefer on my 4 stage; BRS 4 Stage Valve replacement filters comes with prefilter chloramine carbon filter and color change DI. Spectrapure Premium RO membrane, these are hands down the best out there. Hand selected and tested to ensure 90 gpd membrane at 98-99% rejection at 60 psi. This combo makes a great setup, is low in cost and makes DI resin last 100-200% longer than a 95-97% rejection membrane.

LCC · May 11, 2018

I am not a fan of color changing DI resin. It is convenient do to the color change, but it costs more and doesn't seem to last as long in my systems as the non color changing.

chipmunkofdoom2 · May 11, 2018

For what it's worth, your prefilters should be replaced on a 6 month schedule (or as testing indicates). Your final TDS is not a good indicator of when your sediment filter and carbon blocks need to be replaced.

The prefilters mainly protect the RO membrane from chlorine/chloramines and large particulate matter. Chlorine in particular is pretty hard on TFC membranes. You likely can expect shorter membrane service life if you don't keep up on the prefilter replacements.

salty joe · May 12, 2018

Thanks a ton for all that good info! It's very much appreciated. I bought new Dow filmtec membrane-I didn't realize handpicked membranes were available, I'll check that out next time. Thanks!

William Robinson · Feb 13, 2020

First dont freak out...lol I have used my well water for several years in my reef tank with a few issues but none that really bothered me. It is a 600ft deep well and I had it tested for in short "the bad stuff" and it was negligible amounts or zero. I recently began dosing and figured out very quickly setting up the dosing regiment is very difficult when your well water in bringing in calcium, magnesium etc. so I have decided to finally go RO/DI.
My question is... My well water is high in sediment, I am going to run a 6 stage unit from BRS but notice the 1st stage sediment filter is a 1 micron filter. I was thinking of adding in an initial sediment filter setup prior to the unit.
Any suggestion based on my 3rd grade sketch below from those with similar issues?
In Ex2 the reason for the "T" connection is my thinking the high sediment may build up quickly and this allows a longer life if a single 5, 1 setup is good.