Cation-resin-only adverse effects?

[Mierzen]

Hi

I recently bought replacement resin for my RODI unit, but cation resin only...
I now have a situation similar to a previous discussion - the resin increases the TDS (conductivity, rather) of the water (from 3 to 12 ppm).
My question is now this:
Will the excess H+ ions in my water have any adverse effects if using this as top-up water for a 100L tank, while I wait for a delivery of anion/mixed resin?

Hopefully I can get my hands on anion resin, then I'll add another same-sized resin chamber. Otherwise, I guess I will have to replace the anion resin with mixed resin, instead of just putting mixed resin in an additional chamber? The amount of cation resin will still exceed the anion resin in the latter case.

 

[Randy Holmes-Farley]

Yes, this is a terrible plan to operate until you get an anion or mixed bed resin too. The water is very acidic and will deplete tank alkalinity and lower pH.

 

[Mierzen]

Great, thanks.

Case 3 below, arguably, would be best. Between case 1 and 2, I presume 1 is the better one?
1. Only one chamber mixed bed
2. One chamber cation + one chamber mixed bed
3. One chamber cation + one chamber anion

 

[Randy Holmes-Farley]

Great, thanks.

Case 3 below, arguably, would be best. Between case 1 and 2, I presume 1 is the better one?
1. Only one chamber mixed bed
2. One chamber cation + one chamber mixed bed
3. One chamber cation + one chamber anion

All three will work fine.

Unless you have excessive CO2 in your source water (like a well), or want to recharge resins yourself, then mixed beds are usually easier and simpler, IMO.

 

[Mierzen]

All three will work fine.

Unless you have excessive CO2 in your source water (like a well), or want to recharge resins yourself, then mixed beds are usually easier and simpler, IMO.

Without actual tests, we wouldn't know. Let's assume my tap water is average.

I already have quite a large bag of cation resin on hand. I'm not planning on regenerating it, since it wasn't that expensive. Still, if I can use this, it would be nice.

I thought Option 2 would not be ideal (with average water), because the cation-anion resin ratio will be approx. 3:1, and there will still be a H+ excess (albeit less than with cation resin only)?

 

[Randy Holmes-Farley]

Without actual tests, we wouldn't know. Let's assume my tap water is average.

I already have quite a large bag of cation resin on hand. I'm not planning on regenerating it, since it wasn't that expensive. Still, if I can use this, it would be nice.

I thought Option 2 would not be ideal (with average water), because the cation-anion resin ratio will be approx. 3:1, and there will still be a H+ excess (albeit less than with cation resin only)?

In option 2, you might deplete the anion part of the mixed bed first, and will then need to toss it. Using the cation resin before it may not save anything since the mixed bed needs replacement as soon as either part is consumed.

 

[Mierzen]

I guess close to a 1:1 resin ratio would be good, without testing the tap water.
One of the two in the mixed bed will surely be depleted before the other, in which case it should be tossed.
I guess as either resin in the mixed bed get spent, the TDS measurement will increase because of bypassing ions, or newly-introduced excess H+/OH+.

***

I guess if I can source anion resin, I go for option 3.

If I can't, I will be buying a bag of mixed resin anyway. To rephrase my last question: I'm scared by still using the separate cation chamber without a reason other than "because I already have it", I'll be causing more problems for myself.

For average water, if using only cation resin is bad, wouldn't a 3:1 ratio still be "not good enough"?

Would there be an advantage to using cation resin before the mixed bed?

 

[Randy Holmes-Farley]

I guess close to a 1:1 resin ratio would be good, without testing the tap water.
One of the two in the mixed bed will surely be depleted before the other, in which case it should be tossed.
I guess as either resin in the mixed bed get spent, the TDS measurement will increase because of bypassing ions, or newly-introduced excess H+/OH+.

***

I guess if I can source anion resin, I go for option 3.

If I can't, I will be buying a bag of mixed resin anyway. To rephrase my last question: I'm scared by still using the separate cation chamber without a reason other than "because I already have it", I'll be causing more problems for myself.

For average water, if using only cation resin is bad, wouldn't a 3:1 ratio still be "not good enough"?

Would there be an advantage to using cation resin before the mixed bed?

Mixed beds often have an excess of anion resin to bind CO2 as carbonate since it depletes anion resin and not cation resin.

 

[Mierzen]

Mixed beds often have an excess of anion resin to bind CO2 as carbonate since it depletes anion resin and not cation resin.

Thanks.
Would you recommend using only one chamber mixed bed, or also putting the cation that I already have in front of the mixed bed?

 

[Randy Holmes-Farley]

Thanks.
Would you recommend using only one chamber mixed bed, or also putting the cation that I already have in front of the mixed bed?

I recommend optimally folks use two mixed beds in series. I don't see an advantage of using a cation resin and a mixed bed compared to a mixed bed alone.

 

[Mierzen]

I recommend optimally folks use two mixed beds in series. I don't see an advantage of using a cation resin and a mixed bed compared to a mixed bed alone.

Thanks for your insights, Randy. It was a learning experience.