TDS problem

[nevermore84]

I'm looking for any suggestions on how to lower the TDS in my well water.

Water comes out of the well at about 620 on the TDS meter. After I run it through RO/DI it is about 200. Can anyone suggest a way to lower it to acceptable levels? Thanks

 

[Paintbug]

what type of RO/DI unit are you using now? how old is it?

 

[smleee]

Yes, what unit and how old? With a properly installed and functioning DOW FilmTec membrane and ~620 TDS input, you should be getting about 12 TDS after the RO and 0 TDS after the DI. I think your membrane may be spent and your DI exhausted.

eee

 

[nevermore84]

A link for the unit is pasted below

http://www.hbwatersystems.com/html/aquarium_filters.html

I'm not sure how old everything is becasue I bought it used. I did order replacement filters. Should I just replace the membrane as well?

 

[smleee]

Not sure what unit it is, there are a few on that page, but at any rate yes, buying new prefilters is a must since you do not know how old they are. Remember to replace all prefilters every 6 months because of possible bacteria and virus growth (even more important if you're drinking the stuff!). The next step is to get your new filters in there and a pressure gauge if you don't have one already and test the RO only output. At 50psi (if you are around ~35psi or less you may want to get a booster pump) you should be getting a 98% rejetion ratio if you have a DOW FilmTec membrane. So depending on what the TDS is coming from your RO only output this will tell you if you need to get a new membrane. Then test the RO/DI output this should be 0 if you are getting good rejection from the membrane the DI will have to do less work, if not, it's time to replace the DI also.

eee

 

[AZDesertRat]

I would suggest you start fresh with a new membrane and all filters. New prefilters and carbon filters will have little or no effect on your TDS. The definition of TDS is Total Dissolved Solids, the key work being dissolved and those filters only trap Suspended particles (TSS or Total Suspended Solids)larger than 1 micron or whatever the filters are rated for. They basically do nothing for dissolved solids which is where the membrane comes in.
A Dow Filmtec 75 GPD is the best RO membrane you can but for your needs. As for the prefilter and carbons, DO NOT use 1 micron prefilters in a well situation. Wells and groundwater almost always contain small amounts of sand, silica and other suspended particles. 1 Micron will clog much too quickly in these situations. The best bet for you is a 10 micron prefilter followed by a 5 micron carbon block followed by a 1 or 0.6 micron carbon block. That way each filter only traps what it can handle and passes the rest to the next one down stream, 10, 5, 1, RO. None fails prematurely and all share in the load.

 

[Jeff_edge540]

I agree w/ DesertRat.