CO2 Scrubber?

[Taqpol]

While browsing around I found a link to a group called MCU Research that markets a "CO2 Scrubber" for reef tanks. I have a direct link to their product here.

In principal it seems really, really cool as I have some low pH problems due to increased household CO2. I also can't open the windows for a majority of the year (burning hot summers AND freezing cold winters), and since I rent my apartment I can't really make the proper modifications to run my skimmers air intake outside.

First of all, does anyone think their product will work? If piping the skimmer outside is enough to raise pH then it seems to me chemically reducing CO2 levels at the intake would be just as good, I was just wondering about the efficiency of a "passive" system using this chemical.

Secondly, their product is expensive and from the look of it would be a really easy DIY if I knew what type of chemical they used in the reusable media cartridge. I know that CO2 scrubbers used on spaceships/submarines use Lithium Hydroxide, but in one review I found someone that I assume is involved with the company said they do not use Lithium Hydroxide. Do any of the chemistry gurus here know what type of chemical media can remove CO2 from the air?

[kaskiles]

I believe someone at glass-box thought it was something from scuba:
http://glassbox-design.com/2009/soda...-mcu-research/

If your tank and sump are open top, with lots of powerhead flow and fans cooling the water; I doubt you'll get much pH rise from feeding the skimmer low CO2 air.

[mick243]

damp calcium hydroxide is very cood at removing co2 from air....


an easy DIY co2 scrubber would be a bottle 1/2 full of saturated kalkwasser, air goes in a tube thats submerged and bubbles to the surface, and air is taken from the top of the sealed container via another tube into the skimmer intake. if you want a visual indicator of when its used up, use a pH indicator - when its pH drops below 10ish its time to replace.

[Boomer]

Alex

I think those people were reading my posts here on RC, like some others, to sell my ideas, as that years ago was referred to as "Boomer's CO2 Stripper". The media is more or less the same as FW ammonia remover, De-Nitrate (SeaChem), Nitrate Sponge ( Kent) or any of the ZEOvit type media. The are the mineral Clinoptilolite or similar Zeolites. I was also, long ago, looking for a way to purge the CO2 from the media so it could be reused but never went any further. Also, artificial zeo's are better at it.

Here is our discussion on CO2 scrubbers

http://archive.reefcentral.com/forum...&highlight=PSA

http://archive.reefcentral.com/forum...clinoptilolite

I will add that kaskiles is somewhat correct. High room air CO2, if you have it, will always be fighting it without removing much CO2 from the system to get the pH back up. As Mike pointed out, a Kalk CO2 scrubber is probably more effective.

[Taqpol]

Originally posted by kaskiles
I believe someone at glass-box thought it was something from scuba:
http://glassbox-design.com/2009/soda...-mcu-research/

If your tank and sump are open top, with lots of powerhead flow and fans cooling the water; I doubt you'll get much pH rise from feeding the skimmer low CO2 air.

Yeah, I found that review right after I made this post and they say it is Soda Lime that you can buy from medical supply stores. Still, as you and others have stated I don't know if it would help as much as a kalk reactor.

Originally posted by boomer
Alex

I think those people were reading my posts here on RC, like some others, to sell my ideas, as that years ago was referred to as "Boomer's CO2 Stripper". The media is more or less the same as FW ammonia remover, De-Nitrate (SeaChem), Nitrate Sponge ( Kent) or any of the ZEOvit type media. The are the mineral Clinoptilolite or similar Zeolites. I was also, long ago, looking for a way to purge the CO2 from the media so it could be reused but never went any further. Also, artificial zeo's are better at it.

Here is our discussion on CO2 scrubbers

http://archive.reefcentral.com/foru...6&highlight=PSA

http://archive.reefcentral.com/foru...=clinoptilolite

I will add that kaskiles is somewhat correct. High room air CO2, if you have it, will always be fighting it without removing much CO2 from the system to get the pH back up. As Mike pointed out, a Kalk CO2 scrubber is probably more effective.

Thanks for the links and the quick response!

Originally posted by mick243
damp calcium hydroxide is very cood at removing co2 from air....


an easy DIY co2 scrubber would be a bottle 1/2 full of saturated kalkwasser, air goes in a tube thats submerged and bubbles to the surface, and air is taken from the top of the sealed container via another tube into the skimmer intake. if you want a visual indicator of when its used up, use a pH indicator - when its pH drops below 10ish its time to replace.

I use a skimmer with a venturi right on the skimmers recirc pump. If I used a setup like this would the venturi still be able to pull air "through" the saturated kalk mix? Even if it did, would it significantly reduce my air flow and skimmer performance?

Its a really interesting idea.

[Jeremy B.]

I have been using one that MCU sent me for the last day and a half now. Obviously that's not much time for a good review, but so far the results have been promising in my opinion. There are some issues with it in regards to restriction of air intake into your skimmer, however Joe @ MCU is sending me a new cartridge tomorrow that will hopefully fix that.

[Boomer]

Jeremy keep me up dated on how things go

[Jeremy B.]

Just an update on this.....

I have been running this scrubber for almost a week now and the differences it has made in ph are definitely noticeable. On a 100gal volume system, running an a skimmer that is pulling 2000LPH and all air being pulled through the scrubber I have seen the ph of the system go from the 7.9 - 8.1 to now running at a low of 8.3 and a high of 8.53. I also run a calcium reactor on this setup, and the system is in an office where it does stay pretty closed up and isolated from the warehouse.

Just my experiences so far.

[Boomer]

Thanks Jer it should work fine for many tanks. Those that have high room air CO2 may not see much.

[Taqpol]

Originally posted by Boomer
Thanks Jer it should work fine for many tanks. Those that have high room air CO2 may not see much.

Is this because the skimmer is not as significant an aeration source as the diffusion of gasses across the surface area of the tank? For some reason I thought it had more of an affect on good aeration and dissolved O2 then diffusion alone.

[rick s]

Hi Boomer,

I’m not trying to be a smart-aleck. I’m simply trying to understand, and now I’m confused.

If I read you correctly, you’re saying that this might not help the people that have low pH issues due to excessive CO2 in the house.

I’m believing that would be the majority of us. No? I know my low pH is due to CO2 because it only occurs when the house is closed up. So, I guess my question is: Is it possible to have high CO2 in the tank water but not in the house?

Also,
If the benefit of this scrubber is to remove the CO2 from the (house) air entering the skimmer: I do that now by feeding my skimmer’s air input with a fresh air line that is ducted to outside the house. So, would you not anticipate any benefit from this scrubber?

Thanks,

[Boomer]

No, it has to do with the level of high room air CO2. Skimmers are much better than surface diffusion when it come to CO2 or O2. Although the scrubber would be taking CO2 out of the incoming room air feeding the skimmer there would still be high room air driving into the tank itself lowering the pH. It is on the same grounds, somewhat, as having outside air feeding your skimmer (no scrubber) when you have high room air CO2. It does not do all that much.

The issue with the scrubber is we do not know how much CO2 it takes out of any air, where as the Lime unit can take it all out of the air feeding a skimmer. If this scrubber can remove as much as a lime unit then yes it will help the same. Either of these units are best when there is no high room air CO2. Think of it this way Taq, it is a pressure thing. High room air CO2 has more pressure than that in the tank. So, what happens ? The flow of the CO2 is from high pressure to low pressure, so it goes right into the tank. If there is no high room air CO2 then the pressure of both are the same or about the same and now the scrubber works great. If on the other had the tank has more CO2 than room air then just the skimmer can drive off CO2 and raise the pH. Even though the tank now has less CO2 than the air( or equal to it), it is not much and the constant aeration by the skimmer is able to keep up leaving the tank with slightly less CO2 ( or equal to it) than the room. So, the pH goes up. If you know shut off the skimmer the pH will go down and in time will equilibrate with the room air and give x pH. Why is the pH going down ? As it is much easier to drive off CO2 via aeration and much harder for CO2 to enter via diffusion. So, CO2 is now rising in the tank faster than it can leave by diffusion and the pH goes down. We are trying to beat the diffusion rate. You see the opposite in FW planted tanks, where the plants remove CO2 form the water faster than it can enter via diffusion. So, what happens, the pH goes up. So, what do many do, they inject the water with CO2 to get that high pH down.

[Boomer]

If I read you correctly, you’re saying that this might not help the people that have low pH issues due to excessive CO2 in the house.

It will help but may or may not be that much. Meaning if you did not have high room air CO2 and used the scrubber the pH would be higher in the tank than with high room air CO2. The only thing you are stopping is the CO2 feeding the skimmer, which does nothing for the CO2 air feeding the tank.

So, I guess my question is: Is it possible to have high CO2 in the tank water but not in the house?

Oh, you bet for sure and is a issue for many. Very good aeration should take care of this.

Also,
If the benefit of this scrubber is to remove the CO2 from the (house) air entering the skimmer: I do that now by feeding my skimmer’s air input with a fresh air line that is ducted to outside the house. So, would you not anticipate any benefit from this scrubber?

It may it depends on how much CO2 the scrubber can remove and how high the room air CO2. Some have lots more room air CO2 than others. Like I said in the above post it is kinda like feeding your skimmer outside air with no scrubber. For some this seems to work fine but for others it really does not help much. We need to test this scrubber in a house with low pH issues due to known high room air CO2 to really see what it is doing, vs a skimmer with just outside air. I would conclude it will help but not as much as one may wish as the room air CO2 is just to high.

There is only one way to get around high room air CO2 if one cannot fix their house of it. You run a duct work from the outside to one end of the hood and another duct work to the other side of the hood. One duck work is pulling in outside air via a fan and blowing it across the surface of the water, the other duck fan is pulling out the air via a fan and blowing it back outside. You now have a zero high room air CO2 effect.

[Taqpol]

Ok, so in a high CO2 environment the rate of diffusion across the water would still be too great to be pushed in the opposite direction by CO2-less input air on the skimmer. Does this mean if I was able to duct outside air to the fish tank I would still have low pH problems if I still kept the house closed up?

Also...

Originally posted by Taqpol
I use a skimmer with a venturi right on the skimmers recirc pump. If I used a setup like this would the venturi still be able to pull air "through" the saturated kalk mix? Even if it did, would it significantly reduce my air flow and skimmer performance?

Its a really interesting idea.

I never got an answer to this. Would the venturi on a skimmer be able to pull gasses through the kalk slurry attached to the input line?

[ct_vol]

Hey Boomer,
I just sent Jeremy an e mail about this product and he pointed me toward this thread... My pH is almost always about .25 lower than where I would like it to be... I have been using kalkwasser to give my pH a kick in the rear whenever I get a chance, but that gets old... I am hoping this product will work for me, but I have no freaking clue what you are talking about with the "high room air CO2"... I passed college Chemistry I and II, but thats about the extent of my knowledge... lol Can you break it down for me in laymen's terms???

Thanks,
Randy

[rick s]

Boomer,

First of all, thank you for taking the time to add all of your knowledge for the rest of us!

Somewhat of a side topic:
You and kaskiles have me thinking. Would this work?
The pH of the effluent out of a calcium reactor is low because that is how the device works. Could we take that effluent hose out of the calcium reactor and run it through the "container of kalk?" If that would work, that would bring the pH of the effluent right back up.

[tmz]

I think the high ph resulting from the kalk in a small container would cause the dissolved calcium carbonate from the reactor to precipitate. So you would not have dissolved calcium carbonate entering the tank defeating the purpose of the reactor.

Some do run the effluent through an extra course of aragonite( reactor media) to dissolved even more calcium carbonate and raise the effluent ph a little in the process but a concentration kalk would raise it past the point where the dissolved calcium carbonate would stay in solution.

Others dose kalk to teh tank/system and use a calcium reactor. I do this and they can balance each other off very nicely in terms of ph while providing plenty of calcium and alkalinity to the system.

[Boomer]

Taq

Ok, so in a high CO2 environment the rate of diffusion across the water would still be too great to be pushed in the opposite direction by CO2-less input air on the skimmer.

Yes as you are only fixing the skimmer air and not the room air which is still an issue. But yes, you are removing some of the room air CO2, as the medai is filtering out CO2 form the air. The issue is how bad is the house. However, if you had enough of these scrubbers, not feeding the skimmer but ran room air though them the CO2 room air would drop as the media is adsorbing the CO2 from the room air. But that would be pricey.



[/b]Does this mean if I was able to duct outside air to the fish tank I would still have low pH problems if I still kept the house closed up?[/b

If you run the duck work as I described you will have no high room air CO2 issues in the tank, as the CO2 above the tank will be the same as the outside air. Any high room air that enters under the hood will just be pushed out side.

Now lets pretend you have a sump and that is not really part of the tank / say. That will still be affected by high room air CO2 but so what. As that water enters into the system, if you have a descent surface agitation, that CO2 will leave via agitation at the surface tank water and also be pulled outside by the fan. There are a couple of guys that have done this and it works great. I did not "invent " this. Even if you had no hood and just duct worked outside air into that room and another duct pumped it outside the CO2 in the house will drop. It is the same thing as opening the windows. In northern climates where you really can not do this you just use the hood method and then add a small blower heater to the incoming air duck to warm it up.

You have to find a means to filter the CO2 air out of the house, remove it from the house, through air exchange or remove it from under the tank hood at least. If you just blow some outside air over the tank that is not going to do much, as the high room air CO2 is still in the house. That will cause an even greater differential pressure gradient in the house to the outside, as you are pumping in air, so to speak but not pumping any air out. So, the house will "leak" air out and heat or AC with it through any crack it can find. See air excahnge link below.



Randy

"high room air CO2"

When you breath and when you run appliances they give off CO2 and can create high CO2 in the house. That CO2 goes into the tank and lowers the pH. If one has a pH monitor and has a big party in the house, which is all closed up, all that CO2 from those people will drop the pH of your tank like a rock. It is the same thing as taking a glass of water and putting a pH probe in it or some pH indicator. Then take a straw and blow in the glass, the pH will drop like a rock from the CO2 you blew into the glass. And in case you ask, I do not care what kind of Alk, even 15 dKH or more, CO2 will drop the pH. The CO2 in the house is accumulation because it can not get outside as the house is "tight", no leaks to the outside, which helps keep the heat and AC in the house. In very leaky houses like mine high room air CO2 is not an issue at all and I loose heat. In many good homes it is also not an issue has they have an air-exchange system, such as a


Air-exchange system
http://www.smarthome.com/3033/HE150-...changer/p.aspx



High Room Air CO2 and Reef Tanks
http://www.advancedaquarist.com/issu...2002/short.htm



rick s

See Tom's (TMZ) post




I think the unit Jeremy is selling will work nice for most. But I do not what anybody to think it will solve all reefers CO2 issues from high room air CO2. I would love to be wrong here It will for sure help with pH IMHO, it is an issue of is it enough for you ?

[rick s]

Boomer,

I've been thinking that an air-to-air exchanger is what I need for quite awhile now. As long as I'm picking your brain: CO2 is heavier than air, correct?

I have a 2-story house and each floor has its own HVAC system. Our bedroom is upstairs. So, for our health's sake, if the CO2 stays or drops to the first floor, it would be best to install the exchanger on the first floor HVAC system. Sound right?

[Boomer]

Yes Rick

If you have a HVAC does it not have an air exchanger that is what HVAC is all about. The V stands for ventilation. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings.



Muscle cars, Lionel trains.

Cool Wish I still had my 70 Nova SS 396 (402 TRW) and Lionel Train set

[Boomer]

Taq

I use a skimmer with a venturi right on the skimmers recirc pump. If I used a setup like this would the venturi still be able to pull air "through" the saturated kalk mix? Even if it did, would it significantly reduce my air flow and skimmer performance?

Its a really interesting idea.


I never got an answer to this. Would the venturi on a skimmer be able to pull gasses through the kalk slurry attached to the input line?

Forgot about this.

I'd bet it will not fair right and lower skimmer performance. You will not be pulling any air through the kalk mix. However, I think one could get it to work by using a bigger container and bigger air pump to fed the kalk mix so the air under the container lid feeding the skimmer is less than the skimmer can use. That also would mean that the container would have positive pressure head to assist the uptake by the skimmer. One could also control this positive pressure with a needle value vent to the outside room so it is not to much.

[Taqpol]

Originally posted by Boomer
Taq

I use a skimmer with a venturi right on the skimmers recirc pump. If I used a setup like this would the venturi still be able to pull air "through" the saturated kalk mix? Even if it did, would it significantly reduce my air flow and skimmer performance?

Its a really interesting idea.


I never got an answer to this. Would the venturi on a skimmer be able to pull gasses through the kalk slurry attached to the input line?

Forgot about this.

I'd bet it will not fair right and lower skimmer performance. You will not be pulling any air through the kalk mix. However, I think one could get it to work by using a bigger container and bigger air pump to fed the kalk mix so the air under the container lid feeding the skimmer is less than the skimmer can use. That also would mean that the container would have positive pressure head to assist the uptake by the skimmer. One could also control this positive pressure with a needle value vent to the outside room so it is not to much.

That makes sense, but I was hoping for more of a passive system instead of having to run an air pump. If I'm going to be running an air pump I think I might as well fork over the money for a kalk reactor and take out two birds with one stone.

[David Grigor]

If your going Kalkwasser:

Kalk reactor IMO/IME is just a waste of money and actually inferior to just using the still resevoir method ( I've used both ). Spend the money saved on a good dosing pump instead.

[rick s]

Originally posted by Boomer
If you have a HVAC does it not have an air exchanger that is what HVAC is all about.

Nope. I've lived in Pennsylvania, New York, Virginia, Florida, Germany, and other places. I have never owned a house that had, nor known anyone that had, an air-to-air exchanger. I am now looking into one though.

Thanks for all your help.

[rick s]

Oops. Clicky to quickly.