RO/DI Pre Filtration

[nharwood]

I recently replaced all my RO/DI pre filters (5 micron sediment and two 1 micron carbon blocks). I am on well water and my incoming TDS is high (~350 range).

Anyway, after the filter changes I noticed that the TDS after the filters was higher by about 30 TDS than before the filters (pre membrane in both cases). I've had the RO/DI system for a couple years and never noticed this in the past. I would expect the TDS to be the same or less after the pre filters. Does this indicate a problem or just variation in the sensors?

 

[Opus]

How long after replacing did you get these numbers? I usually make 10 or so gallons on new pre-filters before I hook them up to go to the RO membrane. You should be seeing the same tds after the pre-filters so maybe the carbon blocks have a lot of dust to get rid of or maybe they are bad. Where did you get them? Also, a handheld tds meter is a great investment.

 

[nharwood]

Immediately after replacement as well as after 40 or so gallons. Same readings. I got them from BRS, and I do have a hand held TDS meter, I will try that and see what the readings are.

 

[Opus]

I would think after 40 gallons you wouldn't see that. If the handheld gives you the same readings, then I would contact BRS and see what they say.

 

[AZDesertRat]

You shouldn't see any difference. Sediment and carbon block filters are like 0.2, 0.5, 1, 5 and 10 microns. TDS or dissolved solids are 0.0001 microns, thousands of times smaller than suspended solids.