why do I burn through so much DI resin?

[reefmaster70]

Hello all. Ok, I have always been curious as to WHY I burn through so much DI mixed bed resin in my RO/DI unit. I have a 5 stage unit connected to an RO Buddy pump setup that has the auto backwash setup. My filter stages are a 1 micron sediment, 1 micron carbon block, 100gpd high rejection rate RO membrane and then into a mixed bed resin cannister, and from there into a final mixed bed resin cannister, and then out to storage. My input water goes in about 220tds and comes out 0tds.

I am on a private well, no chlorine, etc. The well water comes into our home, runs through a whole home water softener, and then into a whole home carbon/sediment filter and then on into the rest of the house and to my RO/DI unit.

I can make about 100-125 gallons or Ro/Di water before both DI resin beds are used up and need replacing. Is this normal, or should it be lasting longer than that? I thought about changing from mixed bed to one with Cation and one with Anion resins, but never saw much point in that.

Any thoughts to help me make my resin beds last longer??
Thanks

 

[Aaron75]

Ditch the mixed bed and go for separate. You'll likely find your anion gets used up faster. Separate beds might give you a little more life, if it doesn't, you'll have to consider degassing.

 

[rtparty]

Low pH from your well water

You need to build an off gassing chamber between the RO membrane and the DI resins

 

[reefmaster70]

Low pH from your well water

You need to build an off gassing chamber between the RO membrane and the DI resins

are there DIY's or "how to's" on how to do that? Is it a small unit, or do I have to collect huge amounts of water, and off gas for days, before running through the DI resin?

 

[Aaron75]

are there DIY's or "how to's" on how to do that? Is it a small unit, or do I have to collect huge amounts of water, and off gas for days, before running through the DI resin?

https://www.reef2reef.com/threads/diy-co2-degassing-chamber-for-ro-di.212587/

 

[rtparty]

are there DIY's or "how to's" on how to do that? Is it a small unit, or do I have to collect huge amounts of water, and off gas for days, before running through the DI resin?

You can find them on Google but it’s basically a reservoir that you aerate before pumping it though the DI resin

To be honest, depending on what’s in your well you may not even need DI resin. You may be better off with a sediment, 2 carbon blocks, and the RO membrane. Skip the DI

 

[djkms]

Its all about your membrane. What membrane do you have? The standard rejection rate of average membranes is 96% IIRC. That means that if your TDS going in is 220 then the TDS going from your membrane to your DI Canisters is 8-9. Only getting 100-125 gallons per DI cartridge makes sense actually.

I have 2 99% rejection rate membranes found here:
https://www.saltwateraquarium.com/s...ed-99-rejection-rate-mem-sp-0090-spectrapure/

I flush the TDS buildup for 10minutes before running water through the DI canister and average about 2 TDS going in and get about 300-350 gallons depending on the brand of DI resin I use.

 

[reefmaster70]

Its all about your membrane. What membrane do you have? The standard rejection rate of average membranes is 96% IIRC. That means that if your TDS going in is 220 then the TDS going from your membrane to your DI Canisters is 8-9. Only getting 100-125 gallons per DI cartridge makes sense actually.

I have 2 99% rejection rate membranes found here:
https://www.saltwateraquarium.com/s...ed-99-rejection-rate-mem-sp-0090-spectrapure/

I flush the TDS buildup for 10minutes before running water through the DI canister and average about 2 TDS going in and get about 300-350 gallons depending on the brand of DI resin I use.

I have a Dow Filmtec ultrahigh rejection rate 100gpd.

 

[Tangdora]

Co2 probably the main cuprit. I only get 2-3 months out of a cartridge and maybe 2-250 gallons max. I’ve accepted it at this point but 220 tds is high my well comes I at about 90. Do you know what your tds is before all your water equipment. Sometime that can increases it depending on what media your running. Do you have any water line that branch off the well bladder before the softener. That you could test not uncommon for our hoses to skip all the filtration.

 

[afboundguy]

@reefmaster70 as others have said I would highly suggest upgrading to a triple resin setup with a cation stage, anion stage and then a mixed resin stage. I have high TDS coming in and I added a bunch of extra prefilters and my TDS is 0 after the RO membranes so my triple resin beds should last significantly longer (https://www.reef2reef.com/threads/rodi-upgrade.1153638/)

 

[nextevolution3]

l live in nyc and i been burning through di resin like crazy this never happen before full depleted after 55 gallon drum was filled all, 7 stage rodi unit with booster pump and new membrane and all filters

 

[Shirak]

Could be CO2 with a well. I’m on a well and there is some CO2 but my anion canisters produce hundreds of gallons without exhausting. My guess TDS creep is a more likely culprit whether you are on a well or not.
After shutting off the unit, the tds between the waste side and the RO side will start to equalize. It doesn’t take long for your RO in the membrane housing to get to about half your source water tds. When you turn your system on again it pushes this high tds ro water into your di canisters. The ro membrane also takes a minute for the ro water to reach peak rejection rate.
The best solution is to do what Djkms mentions, and I do the same.. T valve between the RO and DI so you can divert the RO for a few minutes each time you start the system up. Once RO tds has dropped to where it should be, send it to the DI stages.

 

[nextevolution3]

30 tds going in and 0 coming out

 

[Shirak]

l live in nyc and i been burning through di resin like crazy this never happen before full depleted after 55 gallon drum was filled all, 7 stage rodi unit with booster pump and new membrane and all filters

Have you tested RO tds after flushing the new membrane for 10 minutes to make sure it’s working properly?

 

[nextevolution3]

yes and used a different 4 stage rodi system resin depleted very quick and i know 3-4 people that's going through the same thing this has happen within the last month before this everything was good

 

[Shirak]

yes and used a different 4 stage rodi system resin depleted very quick and i know 3-4 people that's going through the same thing this has happen within the last month before this everything was good

What’s the tds of the RO water before going to the DI?
Are you turning the system on and off frequently making small batches of RODI?

 

[Shirak]

yes and used a different 4 stage rodi system resin depleted very quick and i know 3-4 people that's going through the same thing this has happen within the last month before this everything was good

If you’re on municipal water do you monitor for chlorine or chloramine getting through the carbon filter which could ruin the membrane?

 

[nextevolution3]

yes i run a 7 stage will see how long it last

 

[Shirak]

yes i run a 7 stage will see how long it last

What's the TDS of the RO water going into the DI filter?
Are you familiar with TDS creep? That could eat through DI resin pretty fast if you turn your unit on and off a lot.

If you are still burning through a whole canister of DI resin after 55gal of production then it is most likely a problem with the RO not reducing the TDS properly. TDS of your RO water should be around 4ppm roughly. Maybe a little higher or lower depending on your source water.