DI system only system questions

[Syntax1235]

Hello,

I've been using RO/DI for years; however, I've decided to try and reduce water usage by eliminating the RO membrane stage. My system is as follows:

Source water is approximately 34 tds measured by inline tds meter and verified by a pen type tds meter. I also have in-line tds meters after the second carbon block and after each di stage.

1) sediment filter
2) 5-micron carbon block
3) 1-micron carbon block (tds out of the second block is 44) - maybe there is still residue from the carbon blocks as this shouldn't be higher than the source water?
4) cation single resin di block (tds out of this stage is 107)
5) anion single resin di block (0 tds out of this stage)

I don't understand how the tds is so high out of the cation di resin stage.? I just changed out my carbon blocks and flushed them for 20 minutes before hooking up the di stage. The di resin is only a few months old and doesn't show any color change... I'm using the BRS single bed resins.

I'm wondering if anyone can help me understand why the tds is high out of the cation stage.

I'm going to use this system for a while to see how fast I go through the resin. If all goes well, I will add another di stage and be able to eliminate waste water from my water-making process.

Thank you for any insight.

 

[Timfish]

I do not know, however, as I understand, TDS meters are using a voltage to determine TDS. So I'd guess either either your filters are increasing TDS somehow or altering the conductivity somehow to let the meter read a higher number.

 

[Dburr1014]

Hello,

I've been using RO/DI for years; however, I've decided to try and reduce water usage by eliminating the RO membrane stage. My system is as follows:

Source water is approximately 34 tds measured by inline tds meter and verified by a pen type tds meter. I also have in-line tds meters after the second carbon block and after each di stage.

1) sediment filter
2) 5-micron carbon block
3) 1-micron carbon block (tds out of the second block is 44) - maybe there is still residue from the carbon blocks as this shouldn't be higher than the source water?
4) cation single resin di block (tds out of this stage is 107)
5) anion single resin di block (0 tds out of this stage)

I don't understand how the tds is so high out of the cation di resin stage.? I just changed out my carbon blocks and flushed them for 20 minutes before hooking up the di stage. The di resin is only a few months old and doesn't show any color change... I'm using the BRS single bed resins.

I'm wondering if anyone can help me understand why the tds is high out of the cation stage.

I'm going to use this system for a while to see how fast I go through the resin. If all goes well, I will add another di stage and be able to eliminate waste water from my water-making process.

Thank you for any insight.

Something in my head is telling me this is normal, like I read it somewhere.

@Buckeye Hydro you are a rodi guy, maybe you can answer.

 

[Syntax1235]

I should have researched this more thoroughly. I have a post by Randy that explained the raise in TDS... for anyone interested, here's his response to a similar question:

DI Cation Resin Low in / high out

Purchased new BRS resin for my 3 stage DI's. The Cation (#1) is adding 2TDs to the water. 1 in 3 out. This is something new. It did not do this on the last batch. Anyone else have this happen?

www.reef2reef.com

Randy's post:

"A cation binding releases one or two H+ (Rarely 3) for every cation bound. H+ is by far the most conductive ion, so TDS rises and the pH drops.
The anion resin releases one or two OH- (rarely 3) for every anion bound. Hydroxide also conduct very well so the TDS and pH rise.

Then when those fluids combine, the H + and OH- combine exactly to make nonconductive H2O."