Zero TDS...trying to achieve

OA3B · Jan 7, 2019

Hello community
I just received my DI resin tonight. I hooked it up with to my RO buddy. I also added a inline TDS meter. So before I added the DI resin I wanted to see what the TDS was that I was putting into my tank, it was reading 24 ppm. After the resin, the lowest reading was 2 ppm. The unit is rated at 100 gpd and is roughly 2 months old. I took a look at my county water report and there is no chlorimine being added. The piping in my home has no copper. What should or can I do to achieve the purest water?

saltyfilmfolks · Jan 7, 2019

Rinse the cup in rodi water twice before you test it.

Fwiw , the clorine is being taken out by the carbon amd the to membrane.

Indiana Reefin · Jan 7, 2019

You probably need 2-3 stages of DI to knock it to zero.

What is your tds out of your tap?

Ridgeway · Jan 8, 2019

The most common cause of a DI resin not giving zero TDS (assuming it's new resin) is that it not packed tightly enough and the post membrane water manages to channel it's way through the pod and is only partly seeing the resin. Packing a DI pod is quite an art... (or PIA) even if it came pre-filled from a supplier it may still not be well packed or could have settled during transportation. If you have spare resin then i'd suggest to re-pack it.

Basically half fill it, tamp it down by either using a flat implement and applying some pressure from the top or simply tap the base of the pod on a solid surface, i typically do both. Keep do this as you fill it up and then when you reach the top leave NO space for the sponge pad. Then place the sponge pad on (assuming you have one) and screw the cap on, which should be a process of squeezing the sponge and resin down ie so it's all really tightly packed in there. Now the water cannot create channels in the DI resin and has no choice but to be be fully exposed to the resin and you should get a zero (in-line) TDS result.

thejuice24 · Jan 8, 2019

What is your TDS going into your membrane and out of the membrane. The membrane is suppose to have a 95 to 98 rejection rate. At the specified PSI. So if your TDS going to the membrane say was 100 you could expect 2-5 coming out of the membrane and on to your resins. I would expect your TDS to be extremely high coming out of your membrane if prior to changing resins you were getting 24 TDS for product water. Your membrane is the one that sound suspect to me.

I have a RO Buddy as well, I also recommend running dual resins on it. I also tapped on a pressure gauge into the system as well for 15 bucks. At a minimum it’s a extra peace of mind, once we resolve this issue.

Bulk reef supply did a few videos on RODI units that was extremely knowledge full. You should check them out on you tube and just apply it the RO buddy. Everything is the same your just not using the fancy unit. Watching those videos helped me step up my RO water game big time.