Co2 and RODI

[Awais98]

Im in the process of setting up a new system in the new house.
My current issue is the DI resin gets used up VERY fast.... fast like 4 brute cans of RODI and its done! like 100 gallons only.

Been reading, researching and it seems like CO2 may be a problem.
In theory it seems right. Im in San Antonio and we get out city water supply from underground aquifer waters. Which I belive will be like well water.... very hard and now a lot of co2 apparently.
Researched a lot and seems the best way would be to get the RO water degassed in a storage bin and then pump it through the di resin.

4 questions for the knowledgeable.

1: Just checked my CO2 in RO water ( before the DI resin ) using the ph, alk and it comes out between 5-7 PPM. ( A confounding factor could be, its usually hot here, but this morning it is cool...water may be cooler and CO2 may be higher today? )
Is that high enough for the di resin to be used up? How much DI is used to neutralize X amount of CO2?

2: If after the RO I get a TDS between 3-5 with this new membrane, can I install ANOTHER RO membrane in SERIES..... so that the first RO membranes product water that is 3-5 TDS is now the input water for the 2nd membrane and so now 99% clearance of 5, will be very near 0, tds will be 0.05....
Will that work INSTEAD of DI resin??? or is the DI resin removing something else that is important. The Co2 if any will be taken care of with the powerhead mixing the salt, or just sitting in the ATO.
It will solve a hell lot of problems.

3: If I decide to regenerate DI resin... and actually seperate cation and anion in different cannisters....does it doecrease efficacy?
I read some where that I could do 3 cans: 1st cation, 2nd anion and 3rd mixed for perfection....
That way atleast the first 2 cannisters will be easy to recharge relatively quickly without removing them from the cannisters.

4: The water storage tanks will be in the garage, where with the cars can get pretty hot... like 100-110 in summer with 2 cars in there....
Will it harm the air stone degassing process....as the air pump will be using the garage air..... basically asking that with the cars not running but just hot in there, does the garage have a lot more CO2?? I know dumb question, but will be important to address in the planning stages...

Thank you for reading!!

Awais


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[SABOB]

Following this


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[BuckeyeHydro]

1: Just checked my CO2 in RO water ( before the DI resin ) using the ph, alk and it comes out between 5-7 PPM. Is that high enough for the di resin to be used up? How much DI is used to neutralize X amount of CO2?


Treat as if those 7 ppm were just plain ole' TDS. As a rule of thumb, a 10" x 2.5" mixed bed DI cart has a conservative capacity of about 5000 ppm. So, 5000 / 7 = 714 gallons capacity assuming you have no actual/other TDS. But because you have 5 ppm RO water, 5+7 = 12. 5000 / 12 = 42 gallons capacity


2: If after the RO I get a TDS between 3-5 with this new membrane, can I install ANOTHER RO membrane in SERIES..... so that the first RO membranes product water that is 3-5 TDS is now the input water for the 2nd membrane and so now 99% clearance of 5, will be very near 0, tds will be 0.05....
Will that work INSTEAD of DI resin??? or is the DI resin removing something else that is important. The Co2 if any will be taken care of with the powerhead mixing the salt, or just sitting in the ATO.
It will solve a hell lot of problems.

You could do this, but...
Typically when we talk about running RO membranes in series on a residential system it is the waste water from the first membrane that is fed to the second. In your case, you'd want to collect the permeate (RO water) from the first membrane in an unpressurized container, and batch feed it with a booster pump to a second membrane. You could do this, but there is a better solution:
Send your RO water to an unpressurized reservoir, then aerate it to drive out the CO2, and then feed the water to the DI stage.


3: If I decide to regenerate DI resin... and actually separate cation and anion in different canisters....does it decrease efficacy?
I read some where that I could do 3 cans: 1st cation, 2nd anion and 3rd mixed for perfection....
That way at least the first 2 canisters will be easy to recharge relatively quickly without removing them from the canisters.

The typical approach with separate bed resins is cation->anion->mixed bed polisher. Nothing terribly unusual/odd about this approach.


4: The water storage tanks will be in the garage, where with the cars can get pretty hot... like 100-110 in summer with 2 cars in there....
Will it harm the air stone degassing process....as the air pump will be using the garage air..... basically asking that with the cars not running but just hot in there, does the garage have a lot more CO2?? I know dumb question, but will be important to address in the planning stages...

Better to have the stored water in a conditioned space.

Russ

[Awais98]

Treat as if those 7 ppm were just plain ole' TDS. As a rule of thumb, a 10" x 2.5" mixed bed DI cart has a conservative capacity of about 5000 ppm. So, 5000 / 7 = 714 gallons capacity assuming you have no actual/other TDS. But because you have 5 ppm RO water, 5+7 = 12. 5000 / 12 = 42 gallons capacity



You could do this, but...
Typically when we talk about running RO membranes in series on a residential system it is the waste water from the first membrane that is fed to the second. In your case, you'd want to collect the permeate (RO water) from the first membrane in an unpressurized container, and batch feed it with a booster pump to a second membrane. You could do this, but there is a better solution:
Send your RO water to an unpressurized reservoir, then aerate it to drive out the CO2, and then feed the water to the DI stage.



The typical approach with separate bed resins is cation->anion->mixed bed polisher. Nothing terribly unusual/odd about this approach.



Better to have the stored water in a conditioned space.

Russ

Thank you Russ!!
That was very helpful.

I experimented with my current water and this is what I found:

Water pH

RO pre oxygenated 6.2!! Alk 5,Co2:5.5
RO post oxygenation 8.5!!Alk 5,Co2:0 😍

Indoor faucet preO2: 7.5
Indoor faucet postO2: 8.6

Garden hose preO2: 7.5
Garden hose postO2: 8.6





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[BuckeyeHydro]

How long did you aerate the RO water?

[Awais98]

How long did you aerate the RO water?

That was an experiment,
it was 1 pint of water and aerated for 1 hour



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