Extra DI unit

[o.c.d.]

I had a problem with my 4 month old R/O DI unit, first I couldn't get the water below 20ppm, then the sediment and carbon chambers were over tightened or crap and I replaced them,I also replace my sediment and carbon every 3 months,still 20ppm,So thinking the DI may be the problem I ordered a replace that came with replacement DI,Instead of changing out the first unit I just added it to the outflow.Now I have 0ppm,But the last chamber will not fill passed halfway is this a problem or will this cause a problem in the future?

[AZDesertRat]

Not if its a vertical DI canister. The flow goes up through the middle of the internal cartridge so its normal for the space between the cartridge and housing to be only partially full.

[TomRep]

What is the tds of your tap water? 20ppm will wear DI resin down failry quickly. Unless your incoming tds is really high, your membrane should be taking your tds a lot lower then that. What kind of unit do you have? How many gpd? Is your tds meter calibrated?
tom

[o.c.d.]

Tap water is 249ppm It was a optima purely H2O Vision series,Gpd 100 i think??,AND TDS meter is calibrated with distilled water reading 000ppm

[TomRep]

Well, if the TDS coming out of the mebrane was 20, you have a 92% rejection rate, which is good for a 100god unit. If you went with a 75gpd Filmtec membrane, they are rated for a 98% rejection rate. That would bring the TDS out of the membrane to approx. 5ppm which would be a lot easier on your resin. This is all assuming you are getting 20ppm out of the membrane though.
tom

[o.c.d.]

Now it's at 0ppm but Im running it through two DI units 1=20ppm then 2nd out at 0ppm

[rjrobert]

Wow tap is 249? Is it well water or municple? I'm used to hearing TDS of 100-150ppm from municple. I don't think I would want to even drink that water

[TomRep]

lol my tap water is 480, so 249 is nothing! I am on a well and our house was built on a farm field.