"erik" wrote in message ...
3 stages of carbon filtration sounds funny to me.
My Culligan RO unit has a 5 micron sediment/carbon stage followed by
an RO membrane.
Since it's a CTA membrane I'm only getting about a 95% rejection of
"bad stuff"

Hm... you have carbon filter in front of your CTA membrane... strange.
I understand CTA membrane is made from organics (cellulose) and
needs chlorine in the water to kill bacteria chewing on cellulose...
Your carbon filter is removing chlorine from the incoming water...
How long do you use your setup? Is it DIY or purchased complete?