Ro/Di not reading 0 on tds meter

Temp is 76f 70psi, its the lowest I can get with booster pump. from left to right on reading 187x10, 131, 19,
Have to do ratio test 2morrow when I get ,measuring cup

 

Ok I used a syringe and it came to 564 waste and 149 pure the math is 3.79 so it is a 3.79:1 ratio

 

Im going to replace the filters, the current ones are 3-4 months old

 

Sorry I took so long to answer, was out of town for 5 days then came home and started a new job this week.
Are you saying your incoming TDS is over 1800? Is your tap water naturally 76 degrees or are you warming it somehow? Why do you have the booster pump turned down to 70, crank it up to 90-100 so the membrane will function much much better. Membranes are rated for 150 psi and higher, the only weak link is low quality housings or fittings, good ANSI, UPC and NSF rated pieces should have a 125 psi working pressure rating.

Keep in mind, sediment and carbon block filters have very little to absolutely nothing to do with TDS, they are there to protect the membrane from suspended solids, big floating stuff not dissolved solids, and chlorine. 3-4 months may still be OK if you don't have silt, sand or colloidal materials fouling them.

 

Yes its 76 right out of the faucet