[Bonzer]

If I have an RO membrane that is putting out a TDS of 5, is there really any need to polish it to zero with a DI?

[welmac]

up to you mate!

i know people who refuse to work with water above 001ppm, then there are others who work with it at 020ppm 

TBH though if you do polish it with resin, the resin is going to last quite a while at 005ppm so its not as though its going to be very costly. if it was me i would use resin, plus it does look good when you can show customers/potential customers how pure your water is 

Gary - WELMAC SYSTEMS

[JM123]

gotta agree 100% with gary, we don't allow our water to go above 1 ppm in the static tanks, then all the water is di'd again between delivery tank and pump, we never ever have to worry about how good the water is, plus the resin lasts for ages, we spend no more than £100 a year on resin for 3 del units. (although we do take very good care of the merlin, sed filter every month, carbon prefilter every 2 months and backflush every week at least once)

[alansavvi]

I was running at 1 now it is 2, i would run it until it was about 6 then i will service the system.

[Londoner]

Im sure its OK up to 5 but I can't work with it. It just causes me anxiety and stress.
Zero or 1 but then I change the resin. Why risk it?