I'll rent that test kit from you once you're done. Been following this since I'm experiencing a similar situation.
4 stage system. TDS of water into RO stage = 146. TDS out of RO = 3 for 98% efficiency. Lucky to get 250 gallons of '"0" TDS water from a pound of DI resin.
I used to use Spectrapure MAXCAP resin and got about 500 gallons from a pound of resin. When they stopped selling maxcap in bulk, I switched to BRS resin and saw the drop in longevity. Tried a few others since with the same result. Was going to try buckeyehydro's semiconductor grade next, but doubt that it will last any longer.
4 stage system. TDS of water into RO stage = 146. TDS out of RO = 3 for 98% efficiency. Lucky to get 250 gallons of '"0" TDS water from a pound of DI resin.
I used to use Spectrapure MAXCAP resin and got about 500 gallons from a pound of resin. When they stopped selling maxcap in bulk, I switched to BRS resin and saw the drop in longevity. Tried a few others since with the same result. Was going to try buckeyehydro's semiconductor grade next, but doubt that it will last any longer.