"erik" wrote in message
...
No DI yet. I'm looking into building one. PVC pipe is cheap )

Anyway, 40 ppm TDS may still be high but if I'm getting a 90 to 95 %
reduction in TDS after the RO should I be expecting better of a CTA
membrane?



When I see 40ppm reading from TDS and want to consider this to be a puriest
source water mix for a reef tank, I would hestitate a bit. But for human
consumption, than, I would say ok. 40ppm reading, will cause algae war /
battle to eternity and normally algae will have the advantage over you. I do
not know much regarding CTA type membrase in RO but as general RO concern,
it should bring down to something like 10ppm or so with TFC or similar
membrane.

With 40ppm, I would suggest using DI unit to further reduce this
filteration. Or change your membrane beside CTA and see if you have better
result without DI unit.

CapFusion,...