Well, I opted for the dual inline to make calculations a little easier. I setup my RO
under my kitchen sink. I also did the calculation and found my system is on at about 54% effeciency. Not good. Anything below 80% is grounds for replacement membrane. I found a great deal on a membrane too ; ) like $63 with shipping from Rocky Mountain Discus (50GPD TFC) Between the TDS
meter and new guage kit coming, I'll know well ahead of time before it degrades so much.