CO2 and RODI

[awais98]

Posting it here so I may get attention from the obvious

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!!

 

[hawkinsrgk]

I can answer question 2:

Short answer yes.

That is the way I have mine setup except I have the waste line from the first membrane going into the input of the second membrane. Sounds like what you are wanting to do is have the output line from membrane one as the input line into membrane two. The downside to this setup is that you will have a lot of waste water since you will be splitting the clean line again. You may already know that and not care, but wanted to through it out there just in case.

 

[awais98]

I can answer question 2:

Short answer yes.

That is the way I have mine setup except I have the waste line from the first membrane going into the input of the second membrane. Sounds like what you are wanting to do is have the output line from membrane one as the input line into membrane two. The downside to this setup is that you will have a lot of waste water since you will be splitting the clean line again. You may already know that and not care, but wanted to through it out there just in case.

Thank you for your reply.
What you are doing is basically making it double output. For E.g. 75 G /day to 150 G per day.
Your aim is to increase product water and reduce waste water.

My aim of wanting to do what I said, is to see if I can get rid of DI resin altogether.
And not sure if it will be ok.
I agree it will waste more water..... but I guess cheaper than changing resin q 100 Gallons...

 

[hawkinsrgk]

Thank you for your reply.
What you are doing is basically making it double output. For E.g. 75 G /day to 150 G per day.
Your aim is to increase product water and reduce waste water.

My aim of wanting to do what I said, is to see if I can get rid of DI resin altogether.
And not sure if it will be ok.
I agree it will waste more water..... but I guess cheaper than changing resin q 100 Gallons...

Yea, I totally see where you are coming from. That is correct, my aim was to increase production and reduce waste water.
Depleting resin after 100 gallons would be crazy expensive. I would probably hook 3 in series if I had that situation. I read about somebody using well water and having super high silicates. They basically took the DI offline because it was depleting so quickly.

 

[Randy Holmes-Farley]

Hot air and water will help drive out the CO2.

Separate DI cannisters are no less efficient.

A second RO membrane will still past most of the CO2. It will also be less efficient than just one for a few reasons, not the least of which are pressure drop and the fact that the easiest to penetrate ions (ammonia, silicic acid, etc.) get through the first, so have an easier time also getting through the second than the average ion.

 

[awais98]

Hot air and water will help drive out the CO2.

Separate DI cannisters are no less efficient.

A second RO membrane will still past most of the CO2. It will also be less efficient than just one for a few reasons, not the least of which are pressure drop and the fact that the easiest to penetrate ions (ammonia, silicic acid, etc.) get through the first, so have an easier time also getting through the second than the average ion.

Thank you [emoji4] Randy.
Coming from you make me feel better.

I think I know what I will do.

3 storage tanks: 75G each
RO with air stone degassing, with barrel tender automation( or cerebra automation,if I can), pump pumping to DI cans
3 DI cans: 1st cation, 2 anion 3rd mixed bed
Rodi ato tank
Tank for Salt mixing and peristaltic continuous water change

If you see any issues with above please let me know.

Thank you and thank you everyone!!

 

[awais98]

Happy to report:

Water pH

RO pre oxygenated 6.2!! Alk 5,Co2:5.5
RO post oxygenation 8.5!!Alk 5,Co2:0 [emoji7]

Indoor faucet preO2: 7.5
Indoor faucet postO2: 8.6


Even if there are errors in the ph proble, that still confirms it degassing will solve it down

Garden hose preO2: 7.5
Garden hose postO2: 8.6

 

[Randy Holmes-Farley]

Sounds good!

 

[awais98]

Sounds good!

Thank you

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.

 

[Buckeye Hydro]

Posting it here so I may get attention from the obvious

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?

You can think of that 7 ppm of CO2 as if you read it on your tds meter. If your RO water had 0 ppm tds, you'd use up a standard DI cart in roughly 750 gallons just due to the 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.

Typically when membranes are plumbed in series it is the concentrate ("waste water") from the first membrane that feeds the second. The concentrate comes out of the RO membrane at a pressure near the feedwater pressure. The permeate ("RO water") comes out of the membrane at very low pressure - it just dribbles out. So to run the permeate through another membrane you'd first have to collect it, say in a brute, and then run it through a booster pump before sending it to a membrane. If you sent 5 ppm TDS feedwater to a membrane, as you said, you'd get permeate at something very close to 0 ppm. Like Randy said you'd still have the CO2 in the RO water... but I don't think that would be an issue/problem. It would drive down the pH, but because all the buffers have been removed from the water the pH will readily change when you add anything to the water (e.g., salt).

3: If I decide to regenerate DI resin... and actually seperate 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.

In the absence of more involved design/planning, having a third/final DI cart containing mixed bed resin is a good 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??

The thing that comes to my mind is the need to 1) avoid sucking car exhaust fumes into the aeration process. and 2) provide fresh air in the garage. Is it possible to open the garage door or a window when you're aerating?

Russ

 

[Buckeye Hydro]

The downside to this setup is that you will have a lot of waste water since you will be splitting the clean line again. You may already know that and not care, but wanted to through it out there just in case.

If you run 5 ppm permeate through a second membrane, you'd not need to run the second membrane at the proverbial 4 to 1 waste to permeate ratio. You could probably run it at a 1:1, and recirculate the waste into the feedwater.

Russ

 

[Buckeye Hydro]

Happy to report:
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

Even if there are errors in the ph proble, that still confirms it degassing will solve it down

Garden hose preO2: 7.5
Garden hose postO2: 8.6

What did you do to aerate the water? How long did you aerate it?

Russ