Question on Co2 Scrubber

[Snoopdog]

I have an air line run outside my house to the skimmer intake and I did see a small bump on PH from doing that. What really moved my PH though was opening my windows in my house for a day. Since running the airline outside only helped a slight amount, would I see a benefit from a CO2 scrubber? I am wondering how the CO2 scrubber would help, unless there is enough CO2 in the outside air to also cause an issue? Before I go into the expense of float switches and media I am trying to figure out if it will help. I know that the inside of my house has to have massive amounts of CO2 from looking at the change when I do keep the windows open.

Also this does help my corals because I can see them react well to the increased PH.

 

[Randy Holmes-Farley]

I have an air line run outside my house to the skimmer intake and I did see a small bump on PH from doing that. What really moved my PH though was opening my windows in my house for a day. Since running the airline outside only helped a slight amount, would I see a benefit from a CO2 scrubber? I am wondering how the CO2 scrubber would help, unless there is enough CO2 in the outside air to also cause an issue? Before I go into the expense of float switches and media I am trying to figure out if it will help. I know that the inside of my house has to have massive amounts of CO2 from looking at the change when I do keep the windows open.

Also this does help my corals because I can see them react well to the increased PH.

Yes, but not nearly as much as the open window. The fact that the window worked better than outside air to the skimmer means the tank top aeration with high CO2 air is successfully competing with the lower CO2 air coming into the skimmer. That will keep happening even if the skimmer is getting lower CO2 air.

 

[Snoopdog]

Yes, but not nearly as much as the open window. The fact that the window worked better than outside air to the skimmer means the tank top aeration with high CO2 air is successfully competing with the lower CO2 air coming into the skimmer. That will keep happening even if the skimmer is getting lower CO2 air.

From what I understand, humidity helps the media last longer? If I put a CO2 canister outside the media would last longer? Also the air outside has less CO2 so that would also keep it lasting longer? Normally we are very humid in the south.

 

[Randy Holmes-Farley]

From what I understand, humidity helps the media last longer? If I put a CO2 canister outside the media would last longer? Also the air outside has less CO2 so that would also keep it lasting longer? Normally we are very humid in the south.

Using outside air with less CO2 will make it last longer, and some humidity also helps.

But whether that makes it work noticeably better is a different question.

 

[Snoopdog]

Using outside air with less CO2 will make it last longer, and some humidity also helps.

But whether that makes it work noticeably better is a different question.

I did find a post back in 2018 where a guy said the outside air brought his up around .1, but when he also added the CO2 scrubber pulling outside air he got another .3 or so.

 

[Anubisxii]

I got a new co2 scrubber recently and was wondering why I waited so long I spent months trying to solve co2 issues. It's not as good as open windows 24/7 I lived in South Florida and that's not an option so the scrubbers the next best thing.

 

[Snoopdog]

I got a new co2 scrubber recently and was wondering why I waited so long I spent months trying to solve co2 issues. It's not as good as open windows 24/7 I lived in South Florida and that's not an option so the scrubbers the next best thing.

How do you have yours plumbed? Are you pulling in outside air, recirculating or pulling room air?

 

[William Mumford]

I have a closed loop co2 scubber and it solved my issues. I live in PA I cannot have the windows open all the time so that was one of my only options.

 

[kecked]

i setup a sodium hydroxide bubbler a week or two back. I do see an increase of about 0.2ph units but what I don’t see is the nighttime drop. That’s the goal. I however also started using the balling method over two part so hard to say which made the difference. I really think the base bubbler is better than the pellets. Certainly lasts longer and is cheaper. I should add in a fixed co2 amount and measure the output to figure the stripping power. Bet deeper bubbler better contact time better strip.

 

[jda]

Most of this depends on how much you air out your house. Some folks open a window an inch for an hour and complain that it barely worked. Others will open many windows and even use some fans (in window, or whole house) to exchange nearly all of the air where the effects can be dramatic in a few hours. There is a HUGE difference. We have a 48" attic fan that moves like 12-15,000 CFM and it keeps the pH up in all of my tanks. We run it every day in the spring, summer and fall, but we have to pick only nice days in the winter. A freshly aired out home can go a few weeks being closed up without having the tank pH go down... and we get nice days more often than that, even in Colorado.

Get something powerful to move air and then run it on nice days. The humans in my house appreciate the fresh air too.

All of this said, I had no issues with low pH around 7.8 and high at 8.0 in a closed up house.

 

[ReefBeta]

For me, CO2 scrubber have a lot greater affect.

I live in city. The CO2 outside it's usually 400~500. When I closed windows in the winter, indoor CO2 goes up to 1000.

During summer, all windows are open, pH gets to 8.15 top, drops to 7.9 at night. During winter, pH drop to 7.8 to 8.0.

I installed a CO2 scrubber recently. The pH goes up to 8.35. At night it still remain above 8.2. I run it in recirculation, so that it can last longer.

I think with CO2 scrubber has more impact because it can get CO2 to 0 in the air. ( Just guess, haven't be able to measure that yet). If taking air from outside, CO2 will still be 500 in that air, just like when opening windows.

If your outdoor air has lower CO2, like 300ish, running airline outside will have bigger impact than mine.

 

[ReefBeta]

Difference between 8.1 and 8.3 is huge. I have to increase alk dosing by 30% to keep it from dropping. Is there some chemistry reaction that consume alkalinity in elevated pH? If not, the drop will mean 30% more calcification, from corals and coraline growth.

Haven't had enough time to comparison in actual coral growth yet, but at least some frags that were damaged before when I fought dino are now showing new grow and recovering. There are also a lot more purple coraline appearing all over the rocks.

 

[Randy Holmes-Farley]

Difference between 8.1 and 8.3 is huge. I have to increase alk dosing by 30% to keep it from dropping. Is there some chemistry reaction that consume alkalinity in elevated pH? If not, the drop will mean 30% more calcification, from corals and coraline growth.

Yes, both abiotic precipitation of calcium carbonate and coral calcification increase at higher pH. How much of your 30% is each is hard to say.

 

[kecked]

I have my tank in a greenhouse surrounded by trees and plants so at night I get lots of co2. That’s why I use the scrubber on the skimmer. I tried just turning it off at night and got a little improvement. Now I scrub Leave it on and cover the top of the tank 80%. It limits the swing to 8.4 day 8.3 night. I can live with that. I will turn the scrubber off to see if the difference is really just the balling method I started. I’m betting the night tank cover is doing the most. If so I might put a fish tank pump on the scrubber and pump co2 free air into the space between the cover and water. Bet that will be a bigger difference. Also cuts evaporation a lot. Pain taking cover on and off but it covers with so much condensation I think it would reduce par even if I slant it to keep water off. Then again I’m running my lights at 30% so I could compensate.

ps I over complicate this stuff cuz it’s fun not that it all makes sense.

 

[Randy Holmes-Farley]

I have my tank in a greenhouse surrounded by trees and plants so at night I get lots of co2. That’s why I use the scrubber on the skimmer. I tried just turning it off at night and got a little improvement. Now I scrub Leave it on and cover the top of the tank 80%. It limits the swing to 8.4 day 8.3 night. I can live with that. I will turn the scrubber off to see if the difference is really just the balling method I started. I’m betting the night tank cover is doing the most. If so I might put a fish tank pump on the scrubber and pump co2 free air into the space between the cover and water. Bet that will be a bigger difference. Also cuts evaporation a lot. Pain taking cover on and off but it covers with so much condensation I think it would reduce par even if I slant it to keep water off. Then again I’m running my lights at 30% so I could compensate.

ps I over complicate this stuff cuz it’s fun not that it all makes sense.

Balling (as implemented by Tropic Marin, anyway) will not raise pH as much as a two part based on sodium carbonate , and much less than sodium hydroxide. It won't drop pH as much as a pure sodium bicarbonate two part recipe.

 

[kecked]

Yup I use the brs two part and just started adding in the part C from Marin along with K+ and A- in the calcium and soda ash. Not actual sure what part C is just following a recipe from brs tv. I will say my polyp extension is better...says he after 4 days. I did try the scrubber to put co2 free air between the cover and water last night. Swing didn‘t change at all. Skimmer was off too. I however think 8.4 day 8.3 night is just fine. The cover does help evaporation however. I’m going leave it on and measure par.

randy. Have a happy holiday season and thanks for all the help along the years.

by draager tube the hydroxide scrubber, standard tall reactor 1M NaOH. 500ml/min air flow drops 375ppm CO2 to 40ppm on a single pass. Not bad. I did not make a flow/ concentration vs efficiency chart bit you could predict The exact life of the solution based on starting levels and your skimmer intake flow. I’m sure the efficiency drops as the concentration drops and the ph of the solution doesn’t move enough to add an indicator to say change the solution. I’m sure these table exist for industrial reactors.

anyway cover seems best for me

 

[Randy Holmes-Farley]

Yup I use the brs two part and just started adding in the part C from Marin along with K+ and A- in the calcium and soda ash. Not actual sure what part C is just following a recipe from brs tv. I will say my polyp extension is better...says he after 4 days. I did try the scrubber to put co2 free air between the cover and water last night. Swing didn‘t change at all. Skimmer was off too. I however think 8.4 day 8.3 night is just fine. The cover does help evaporation however. I’m going leave it on and measure par.

randy. Have a happy holiday season and thanks for all the help along the years.

by draager tube the hydroxide scrubber, standard tall reactor 1M NaOH. 500ml/min air flow drops 375ppm CO2 to 40ppm on a single pass. Not bad. I did not make a flow/ concentration vs efficiency chart bit you could predict The exact life of the solution based on starting levels and your skimmer intake flow. I’m sure the efficiency drops as the concentration drops and the ph of the solution doesn’t move enough to add an indicator to say change the solution. I’m sure these table exist for industrial reactors.

anyway cover seems best for me

Thanks, you too!

The carbonate boosts pH, and the hydroxide scrubber is a good plan. I've used it myself in a lab to remove hydrogen sulfide from a waste gas stream, and it will also remove CO2. I'm not sure why more folks do not go this route, and use the expensive soda lime pellets.

FWIW, the Part C will have no substantial impact on pH.

 

[ReefBeta]

Thanks, you too!

The carbonate boosts pH, and the hydroxide scrubber is a good plan. I've used it myself in a lab to remove hydrogen sulfide from a waste gas stream, and it will also remove CO2. I'm not sure why more folks do not go this route, and use the expensive soda lime pellets.

FWIW, the Part C will have no substantial impact on pH.

Tell me more about this hydroxide scrubber? Does it just run the air tube into some hydroxide solution?

 

[Randy Holmes-Farley]

Tell me more about this hydroxide scrubber? Does it just run the air tube into some hydroxide solution?

Yes.

Here's a technical description:

https://www.irjet.net/archives/V5/i4/IRJET-V5I4191.pdf

For a reef, we would just bubble the incoming air air through a water/NaOH solution.

 

[ReefBeta]

Yes.

Here's a technical description:

https://www.irjet.net/archives/V5/i4/IRJET-V5I4191.pdf

For a reef, we would just bubble the incoming air air through a water/NaOH solution.

Very cool. So we use NaOH here instead of CaOH is because the dissolvability, right? Does the concentration of NaOH matter? When bubble directly into the solution, the contact surface is pretty small compares to the reactor shown in the paper, so I guess it will require higher concentration?

Also the depth of the intake will be added to the head pressure of the skimmer air intake, and reducing it, right? If it's in 5" depth, the back pressure of air intake will be similar to having the skimmer running in 5" deeper water, that sounds a lot. So it should be pretty shallow? But then the contact time will be pretty short.