We're getting 250-350PPM and we're making about 4.5 gallons an hour, somtimes as low as 3.3 gallons an hour. I think it's a waterflow problem and not a membrane problem. My intake is only 12 inches below the waterline and the unit is just below waterline. I may have to tap a different through hull if I want to increase water flow. I should have installed a dedicated through hull for it. I had one planned to use but was out voted on installing the second head, which now uses that through hull.

We did the 2 chemical washes on the mebrane and our PPM got better, you might try doing the same to yours. Village Marine Tech is now owned by Parker/Racor so you can get parts and supplies.