DIY CO2 Degassing Chamber for RO/DI

TheEngineer · Sep 3, 2015

Well, I learned the hard way that the water coming out of my well has a high CO2 content. I burned through a pound of DI resin and only got 40 gallons out of it.... To keep this from happening again, I could either buy lots of RO/DI water or remove the CO2 from the RO water before I pass it through the DI resin. (This design is based off of the Spectrapure design.)

Parts List:
3" PVC (36")
3" PVC Cap
3" Knock-out Cap
3" to 1.5" PVC Tee
1.5" PVC Street 90 Elbow
1.5" to 3/4" Reducing Bushing
3/4" PVC (12")
3/4" PVC Threaded Coupling (Female)
3/4" Male Thread to 1/4" Quick Connect Adaptor
Air Pump
Air Stone
PVC primer and cement
Teflon tape

Assembly:
The parts are shown in the image above in the order you would connect them.

Cut the 3" PVC pipe about 6" down
Attach the 3" PVC cap to the bottom of the longer section from step 1
Attach the tee between the two pieces.
Attach the street elbow to the tee and the reducing bushing to the street elbow
Attach the piece of 3/4" PVC pipe to the reducing bushing (you can shorten the pipe if you'd prefer)
Attach the threaded coupling to the 3/4" PVC pipe
Apply teflon tape to the thread-to-quick connect adaptor and thread it onto the coupling from step 6
Drill 3 3/8" holes into the knock out cap
Thread the airline tubing through the bottom of the knock out cap, be sure the air stones are on the bottom!
Insert the knockout cap into the top of the short section of 3" PVC
Attach the air line(s) to your air pump
(OPTIONAL) Secure your air pump to the 3" PVC
Insert the output of your RO filter into the remaining hole of the knock out cap (only insert it a few inches)
Attach your DI chamber to the 1/4" quick connect fitting
That's it!

Use:
To use the degassing chamber, simply run your RO water into the chamber with the air pump running. As the water enters the chamber, it will be oxygenated and the CO2 level will be reduced. When the water level is high enough, it will trickle out of the tee and through your DI resin. Put the output of your DI resin into a bucket or holding tank and it is ready for use.

kschweer · Sep 6, 2015

Nice job! Let us know how it works out for you.

TheEngineer · Sep 11, 2015

I got around to setting everything up and giving it a good test run. I can report success on the primary objective of saving my DI resin from the CO2. I did discover a problem, and I'm working on a long-term solution to it. Gravity feeding the DI resin is not sufficient to keep up with the RO output rate. I dropped the height of the DI chambers down quite a bit and it helps, but still doesn't quite keep up. I'll post back when I figure out something that works (aside from slowing the RO down, that defeats the purpose!)

Buckeye Hydro · Oct 16, 2016

Suggestion: Regardless of if you introduce a small pump to move the RO water through the DI, consider re-routing your tubing so that the DI columns are vertical, and water flows from the bottom to the top of each column. This will help minimize channeling.

Russ

TheEngineer · Oct 16, 2016

Thanks for the suggestion. I've found that the prescreens on my DI canisters must be really clogged and I get very slow flow through them. I need to replace them. For now, gravity isn't enough to push up through them at a rate that would be workable. I'll make the adjustment when I can though.

Buckeye Hydro · Oct 16, 2016

Yep - might want to go with a standard vertical housing with full size 10" x 2.5" refillable DI cartridge with bottom up flow. The cartridges you're using are really intended for GAC media, but you can find them widely used on mis-configured systems as horizontal DI cartridges.

TheEngineer · Oct 16, 2016

Buckeye Hydro said:
Yep - might want to go with a standard vertical housing with full size 10" x 2.5" refillable DI cartridge with bottom up flow. The cartridges you're using are really intended for GAC media, but you can find them widely used on mis-configured systems as horizontal DI cartridges.

That's indeed how they were

ctyler85 · Nov 1, 2017

Any updates on correcting the flow through the DI resin?

TheEngineer · Nov 1, 2017

ctyler85 said:
Any updates on correcting the flow through the DI resin?

Yep. Gave the screens a good cleaning and all is well

ctyler85 · Nov 1, 2017

TheEngineer said:
Yep. Gave the screens a good cleaning and all is well

Awesome, I just picked up the supplies to build one tonight

ctyler85 · Nov 2, 2017

Everything is up and running. However, I was just thrown awake by a realization.... I can't rely on my float valve because it will just cause a flood out of the degasser

Buckeye Hydro · Nov 2, 2017

TheEngineer said:
I got around to setting everything up and giving it a good test run. I can report success on the primary objective of saving my DI resin from the CO2. I did discover a problem, and I'm working on a long-term solution to it. Gravity feeding the DI resin is not sufficient to keep up with the RO output rate. I dropped the height of the DI chambers down quite a bit and it helps, but still doesn't quite keep up. I'll post back when I figure out something that works (aside from slowing the RO down, that defeats the purpose!)

Consider using four 2" housing clips to support your two small, now vertical DI cartridges. Not good practice to hang them from the tubing/fittings like that.

Russ

TheEngineer · Nov 2, 2017

Buckeye Hydro said:
Consider using four 2" housing clips to support your two small, now vertical DI cartridges. Not good practice to hang them from the tubing/fittings like that.

Russ

That was just for testing. I just use one cartridge now and it is supported, not just hanging

Buckeye Hydro · Nov 3, 2017

Couple more suggestions - leave the top of the tube open, or largely open to improve gas exchange. Move the intake of the air pump away from where the CO2 exits the column.

Russ

Buckeye Hydro · Nov 3, 2017

And one more: Reconfigure your DI cartridge for bottom-up flow through the resin.

ctyler85 · Nov 5, 2017

everything went great for the first 40 gallons or so, now the water just overflows out of the top of the degasser.... sitting here staring out it trying to come up with a way to prevent this.

Buckeye Hydro · Nov 5, 2017

Either make the output lower, or the part above the outlet taller. Just like an old counter current protein skimmer.

TheEngineer · Nov 5, 2017

Make sure there aren’t any air bubbles in the DI canister. They’re usually the culprit for me when I get slow flow.

Buckeye Hydro · Nov 6, 2017

Hmm. Even if you have half the housing filled with air, it doesn't affect the flow of water through a standard axial-flow, vertical DI cartridge.

Russ

ctyler85 · Nov 6, 2017

Yeah I'm not sure what the issue is, I guess just flow differential. It's leaving the di canister at a pretty good rate, seems faster then before, but still comes spilling out the top of the degasser, I'm going to attempt to cut it apart tonight and make and length adjustments, also considering maybe adding a diaphragm pump between the degasser and di canister