Vertex Puratek RO Unit Questions

[sphelps]

I would just use the 100gpd membrane, I'm sure the unit is probably built for it anyway so it shouldn't cause any problems. Also the easiest way to tell when to change filters is with a TDS meter, the vertex should have one built in right? Note your TDS with new filters and when it climbs too high for your liking change the pre-filters and DI. There is no exact guideline typically people just change them when they become uncomfortable with the TDS reading, for some that's anything above zero, others around 10, 20, 40 or even 60ppm. Other way is just to use the basic rule of thumb which is once a year. The RO membrane should only require replacing after about 5 years or so. You'll know it's time if you change your pre-filters and your TDS is still too high for your liking.