Can you have too many DI resin cartridges?

[H2OPlayar]

I was watching this video from BRS on DI resins.

In short, they recommend 3 DI resin cartridges; first a cation, then an anion, then a mixed bed resin. I have a few questions that maybe people know the answers to.

Since anion resin depletes much faster than cation, does it make sense to then run 2 anion resins after the cation? Then a mixed resin after? Would 3, 4, or 5 be the most DI resins you want to run your water through? I assume you get some added on pressure for your pump/water pressure to pump through, but are there any other things to consider?

 

[sfsuphysics]

The biggest issue with "too many" is that pressure drops too low, but that's after your RO membrane so I wouldn't sweat it one bit. Besides I don't think DI resin is typically packed so tightly that it provides any significant drop in pressure at least like carbon filters do, could be wrong though.

 

[svreef]

I run 1 cation, 2 anion and 1 mixed bed and I don't have a pump - RO goes directly from a pressure tank through DI and into the sump to top it off.

 

[H2OPlayar]

I run 1 cation, 2 anion and 1 mixed bed and I don't have a pump - RO goes directly from a pressure tank through DI and into the sump to top it off.

That's what I was going to run, but then I have the cartridges to do a second mixed. Seems a little excessive, but the replacement of the cartridges in series speaks to me.

We have talked about plumbing a line from my RO reservoir into my sump area, but that's a big project after the house is already built.

 

[JVU]

Depends on what’s in your water, which is a local thing. BRS talking about Minnesota water has very little to do with your water.

I use 2 mixed beds in series. Been doing it since long before BRS managed to convince people to buy more resin cartridges with their videos. When the first is depleted I get rid of it and move the second to the first spot, new one in the second spot. Has worked great for me for years. 0 TDS, 0 problems. Lasts a long time.

I don’t see any reason to have more DI resin beds than that unless you have a special water source like a well, don’t use an RO stage, or something else unusual. Then you should tailor it to your water, not BRS’s video.

As far as your actual question, the DI cartridges are after the RO filter so adding a little more resistance with another cartridge (or 2 or 3) doesn’t really matter. You are already adding artificial resistance post-RO with the flow restrictor.

 

[svreef]

That's what I was going to run, but then I have the cartridges to do a second mixed. Seems a little excessive, but the replacement of the cartridges in series speaks to me.

We have talked about plumbing a line from my RO reservoir into my sump area, but that's a big project after the house is already built.

I would do more anion instead. The mixed is a fallback and should not deplete until all your anion is depleted