Ro system convert to Ro/DI

GeoHawk · Aug 1, 2011

I have recently realized that I know very little about RO systems I bought mine a year ago, and have never changed the filters because I always got a zero TDS reading. Well I found out I need to change the carbon paper when it goes brown, and also that mine is only RO with no DI. I have this system Store Reverse Osmosis Standard Reverse Osmosis Systems

I was wondering if I can buy this 10 inch DI cartridge and place it in the third stage?
Store Reverse Osmosis Replacement Filter Cartridges | Membranes

Thanks for the help in advance

btkrausen · Aug 1, 2011

Just buy an add-on cartridge to add DI to your current system. Just like this: PR-DI-CONV Premium Aquatics - PR-DI-CONV Aquarium Supplies

You want the water going through DI AFTER it goes through the RO membrane.

AZDesertRat · Aug 2, 2011

You should replace the prefilter and carbon block(s) every 6 months regardless of how much or how little water you have made. They have very little to absolutely no effect on TDS so you cannit gauge their condition with a TDS meter.

You can spend about 10 minutes replumbing your system so the second unneeded carbon block canister becomes a DI canister and only have to buy the DI cartridge plus the prefilter and carbon you already know you need.
Take a look at the CSP-DI Filter Replacement Kit close to the bottom of the page here:
Untitled Document

Its $52 and will get you a much better 0.5 micron prefilter and 0.5 micron carbon block so they protect your RO membrane better plus a filled refillable 20 oz DI cartridge that you can then refill with bulk resin at lower cost.
All you need to do is disconnect the second carbon block canister, move its OUT plumbing to the middle carbon block canister so it now goes up to the RO membrane then rotate the empty canister 90 degrees and plumb the treated RO water to the IN on it and you have RO/DI from the OUT. You might need two 1/4" MIPx John Guest speed fittings available at Lowes or HD for about $3 each.