RO/DI problems

You have some high TDS. I'm not sure what the typical filtration is from the prefilters, but you're getting the typical 95-98% rejection from the RO membrane. I would still think the DI filter should be able to take that to zero. Maybe look at additional stages because of the high initial TDS.

I have also seen brand new BRS DI resin with poor filtering capacity. An unknown brand resin was changed after a 4+ppm output with new BRS resin. No matter how much water was run through it the TDS for the "new" resin wouldn't go below 6. Swapped in my DI cartridge and immediately got a 0 output.


I like BRS, but after seeing that issue with resin, and my recent experience with other filters in my RO/DI I'm sticking with air water ice for my filtering components.


Just FYI I recently had a pressure drop in my unit caused by a prefilter. I was only getting 25psi across the membrane, but still getting 1-2 TDS after the membrane, and 0 after the DI. Output was horrible, but the TDS didn't seem to be effected by pressure.

 

Another thing to look at with that high of TDS is the rejection rate of the RO membrane. Some of the higher GPD membranes have lower rejection rates. You might have better luck with something like a 100 GPD membrane with a proven 98% rejection rate.


http://spectrapure.com/AQUARIUM/MEM...O-Membrane