DI Location

[kjmsmith]

My RO system is a Watts Premier RO Pure and I want to make sure my DI filter is in the correct spot. I’ve had it in position A as noted below as the final stage before going into a pressurized tank. But the more I’m thinking about it, the way my system works would have the water pass through the DI filter and enter the tank but then when it runs to the faucet, it passes in reverse mode through the DI again and this doesn't seem correct. My other option is to put it in position B after the pressurized tank but from what I have read this shouldn't be done because of the high pressure that would be pushing water through the DI filter. One other option I have considered is putting it in position A but have a valve to bypass the DI when it runs to the faucet.
I would appreciate any advice.
Thank you.

 

[W1ngz]

I'm not entirely sure this system would be ideal, because of cartridge number 17 - the carbon post filter. That is going to add new particles and ions to the water after it's passed through the membrane, and your DI resin will have to work at to remove. You may find you burn through resin rather quickly. If you have a TDS meter, check what the TDS of the output water is. If it's any higher than 5, maybe 10 max, then the system isn't suitable for what you want to do. You'll spend the equivalent of a dedicated RODI system in a year just in DI resin.

If you really want to do it that way, then I think either of the blue lines will be fine since, if I understand it correctly, the blue lines are RO water. The trick is, you don't want to put the DI in line with them, you'll want to T off of one.

 

[kjmsmith]

Interesting comment on the carbon post filter. I’ve actually been using this RO system for about 7 years without a DI filter and my output water has been great as far as NO3 and PO4, both at 0. I started having diatom issues a few months back at the same time as high PO4 in the tank. The elevated PO4 is coming from leaching out of the substrate (old tank syndrome?) and I’m thinking the diatom outbreak maybe sourced from silicate in the tap water which led to my recently adding of the DI. Before I added DI my TDS was 14. After adding the DI in position A TDS is zero.
I’m thinking adding a t-valve and manually switching it whether I’m making water (it will pass through DI and into tank) vs when I want to use the water I will turn the valve to bypass the DI may be my best option.

 

[W1ngz]

That will work, but at 14 TDS into the DI stage, I think you'll be using resin quite fast.

 

[kjmsmith]

Thanks for the feedback!

 

[Opus]

It is not advised to drink water that has gone thru the DI process, assuming that is why you have the pressurized tank. The DI material is not food grade.

 

[sharpimage]

It is not advised to drink water that has gone thru the DI process, assuming that is why you have the pressurized tank. The DI material is not food grade.

That is correct. Where on your diagram are you pulling ro out of?the faucet? If so, you could probably put a bypass valve before and after the di at location B. Bypass di for drinking water, go through for RO/DI. Take with a huge grain of salt as I am not sure.

 

[kjmsmith]

I don't use this for drinking water at all - only for my reef tank. The reason I use the pressurized tank is to avoid the need to set up an ATO of some sort to fill a non-pressurized reservoir.

 

[kjmsmith]

I'm not entirely sure this system would be ideal, because of cartridge number 17 - the carbon post filter. That is going to add new particles and ions to the water after it's passed through the membrane, and your DI resin will have to work at to remove.

So I was thinking about the carbon post filter comment about it adding new particles. It appears that water passes through this filter AFTER the pressurized tank when the faucet is turned on. From the manufacturer:

• Carbon Post - A high quality Final Polishing Filter after the water storage tank to remove any remaining chlorine or other chemicals that cause bad taste or odor before being dispensed.

So if this is the case, opinions if I would be better off to run the water line from the tank directly to the faucet and not use the carbon post filter?

 

[W1ngz]

Edit: nevermind, the position of the membrane can't be changed since that position has the line out for the reject water from the membrane.