Adding DI stage to RO drinking water system

[beastium]

I want to add a DI stage to my drinking water filter (below), but I'm not sure where in the plumbing to add the valves.
Here is what I'm thinking to add:
[valve + (tee + valve + DI) + valve]

I was wondering if someone could advise where I might be able to add that? A, B?
And I'm thinking I can't put it at (C) and use pressurized output from the tank.

Here is a diagram of my filter. Note there is an alk stage before the (5) right before it goes to the faucet that's not shown in the diagram:

and the spots I'm thinking I can add the DI filter, which I'm not sure is correct:

My guess is A because I would add a valve right before the ASO that I'd close to operate the DI filter, and the check valve would prevent backflow into the initial stages.

If I put it at B, closing the valve that leads to the pressure tank, the ASO would still be shut and no water would flow into the DI stage. Is that correct?

Sorry if the visuals or info is confusing, I did my best to describe what I'm trying to figure out.

Would it work to add this assembly to point A?

I plan to continue to using this for drinking and bypass/close off the DI stage when I'm not filling up rodi water for the reef.

Any help would be really appreciated

 

[MarineandReef Jaron]

There are a variety of ways to do this. I personally like the way AquaticLife recommends in their Manual. Add the check valve right before the DI resin either after or before the bladder tank.

If you add the T and check valve after the bladder tank you will get quick DI water that is good for cleaning test vials, cleaning glass, etc, but you will also completely empty the tank when you make a lot of water for water changes leaving none stored for drinking. If you T off before the bladder tank you will not get any quick water but you will also leave some water stored in the bladder tank for drinking while you make your large quantities of water for water changes.

 

[Tamberav]

I have mine T'd off after RO.

RO goes to the bladder tank for drinking (DI water is nasty) and DI goes to a barrel for mixing salt or top off.

 

[exnisstech]

I just added a splitter after the membrane. One tube goes to the tank under the sink faucet the other to the di. Been that way for several years and works fine. No valves or anything needed

 

[beastium]

I don't mind having slow rodi output as it's for a smaller tank and I'll be monitoring each fill-up, no float valve.

So if I understood right, T off after RO, and before the ASO valve, so point A would work fine? And add a check valve before the DI?

 

[beastium]

Update: I tried A and didn't get any output, so I installed it at B and it's working like a charm.

 

[heybob]

The DI resin takes TDS to zero, but is it adding chemicals to the water that do not show up on the TDS meter? I would be wary of DI resin adding something like an endocrine disruptor with estrogenic activity. Maybe the "polishing" post-carbon filter removes whatever the resin might add.