What size pump for DI?

[Zayne]

I’m on a well and separating my RO from my DI so I can gas off the CO2. I was planning to run the degassed RO through a 3 stage DI (anion , cation, mixed). The question I have is what sized pump would be appropriate for just pushing through the DI resins? I asked BRS if a PMUP would be strong enough but they recommended getting something stronger, but didn’t really give any range. I wouldn’t have thought that the pressure/power after the RO membrane would be higher than the output of a PMUP.

 

[nereefpat]

The feed to the DI doesn't need to be under pressure. Usually the permeate out of the RO just trickles out.

I don't think BRS knows what they are talking about here.

What about off gassing the CO2 first. Then pumping the water through the whole RODI unit.

 

[Zayne]

I guess that's a possibility, but is there really any benefit in doing so? My house pressure is high enough from the tap to push through the RODI without a booster. I'm currently just running a 5 stage unit from BRS. I'm just getting tired of burning through DI resin ( I get about 75-100 gallons per DI refill. My plan was to add on a second RO membrane via a water saver kit and to get a Triple DI kit and run that after degassing the RO. I already have a few PMUPs.

I also had planned on using the RO only for a freshwater tank water changes (not set up yet) and for dog/cat water refilling.

 

[dangles]

I’d also suggest upgrading your DI setup to a single-bed system with dedicated cation and dedicated anion resin chambers (followed by a final mixed bed). The CO2 will burn through anion resin MUCH MUCH faster than the cation resin.

I have the same issue. I still run through a whole chamber of anion resin every 100 gallons or so but I’m only switching out the anion resin and not wasting the mixed bed just because the anion portion of it is burned out.

 

[dangles]

But to answer your question directly, very little pressure is needed for the DI portion of the filter so I wouldn’t stress that part too much. Whatever works “logistically” will probably be fine.