Sorry, didn't want to bore visitors w/the backstory. Basically, the ro unit is producing too much product h2o and di resin is being used very fast. I've replaced pre-filters, tfc membrane, and even membrane housing. Still no luck. I'm getting about double the product h2o that I should and product to waste water ratio is 1: 2.5. Russ has recommended a pressure reducing valve since our avg neighborhood h2o pressure is 125psi. He's telling me that since psi is above 90, that I'm getting a failure in the unit. Once I get his recomendation about which prv to use, I'll be ordering that along w/a tds meter. Great guy and a great company. They've got my ro business as long as I'm kicking.