The 7th stage in the first one is a waste. It has a GAC
ffilter after the DI
. You can't get better than DI
so what is the GAC
doing at that point.
Also, the 100gph membrane is usually only rated at 90% rejections vs. 99% for the 75gpd or the 150gpd membrane (at least for the Filmtec ones that I've seen).
does not reccomend using a DI
with the 100gpd because of the lower rejection rate. I ran mine that way for 3 years before switchng to the 150gpd membrane.