Secondary DI Resin Tank

[TheMongoose]

With my current 50gpd RO/DI (with booster pump) I still get a TDS reading of around 100. This seems pretty unacceptable and my tank is reaping the glorious benefits of a hair algae all over the place.

Now this is mainly my fault for not getting the filters replaced sooner. But, even in the beginning of it's service the TDS was still pretty high. Around 75 or so.

Yes, a complete filter kit is already on the way and should be here in the next few days.

Now for the DIY portion of this post. I've acquired two 5 liter DI Resin pressure tanks from my work that were going to end up in the trash. Tanks are in perfect shape, it's just cheaper for them to order an entire new kit for change outs.

So, I had the idea to add a secondary DI Resin tank after my 5 stage RO/DI with one of these tanks with the idea that I could get the TDS down to almost nothing and get this tank headed back in the right direction.

Am I understanding the DI resin/TDS relationship correctly in that it reduces TDS in the product water? Or am I way off here?

I understand the cost of resin will be pricey to fill a tank this large but I don't mind if I get some great water quality out of it.

Any input is appreciated so fire away.

 

[ryeguyy84]

New filters should give you 0 TDS water. I'm thinking there is something else going on here. What is the tds leaving your ro membrane?

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[TheMongoose]

Not sure as I'm only monitoring after the final DI stage.

Prior history is always important in troubleshooting so I'll include this info too-
On initial installation I didn't have the booster pump and would have to backflush quite frequently to keep the water flowing. I'm figuring I probably obliterated the membrane in its beginning stages of service.

 

[ryeguyy84]

Even if you run tap water through the di resin it will come out at 0tds as long as the flow is low. What rodi system are you using?

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[TheMongoose]

Liquigen 5 stage RO/DI 50gpd

 

[mcgyvr]

Source water TDS?
Post RO membrane TDS?

Don't know?... Go measure.. adjust your probe point if needed..

100 TDS post DI means that either you are in India sourcing water from some ceespool that the entire community craps in or many/most/all of your filters are shot or you aren't reading output TDS or a few other potential issues..

Knowing TDS at each part of the filtration process is essential to helping you..
Without that valid data we just guess and waste time

 

[TheMongoose]

mcgyvr - That gave me a good laugh. Especially since we get a boil advisory at least once a year here in north LA.

And yeah, I'm definitely going to add some more inline TDS monitoring just to keep a closer eye on things and have more valid data in the future.

 

[TheMongoose]

Just a quick update -

All filters changed and back down to 0 TDS.

One catch though..

My RO/DI system outputs to a 30 gal food grade barrel for storing top off water and after changing filters yesterday I decided it was best to empty the barrel completely so I could refill it with 0 TDS water.

After about 24-25 gallons my TDS was reading 3. Upon inspection of the DI resin, 75% of the resin has changed color showing it's been exhausted already. This seems like an extremely short life span. The replacement prepacked canister w/resin came direct from Liquagen.

Anyhow, I've ordered two more DI resin canisters and plumbing them in parallel for easier change outs in the future.

 

[laverda]

To be that high I would guess your using the waste from the RO unit, not the filtered water. It is impossible to really know what is going on without knowing you tap water TDS and the TDS from your membrane. Use the tester your using to determine your final TDS to measure these and get back to us.

 

[Opus123]

You need to order a handheld tds meter. They are around $20.

 

[Mchava]

After about 24-25 gallons my TDS was reading 3. Upon inspection of the DI resin, 75% of the resin has changed color showing it's been exhausted already. This seems like an extremely short life span. The replacement prepacked canister w/resin came direct from Liquagen.

Anyhow, I've ordered two more DI resin canisters and plumbing them in parallel for easier change outs in the future.

You might want to double check the plumbing on the ro/di system. It might be installed incorrectly. I’m wondering if you’re feeding the waste water to your di media and dumping all your clean ro water down the drain. Post a picture of your system just Incase.

 

[on the spot]

All your fittings are john guest type? You should be able to check all the TDS points in a few minutes with what you have.

It seems likely that Mchava hit it-the plumbing may be suspect.

 

[2000se]

There’s no way your running through DI resin that fast. I wonder as mentioned above if you are pumping the waste water from the RO membrane through by mistake. I don’t need to to tell you something is wrong.