CO2 Scrubber Effectiveness

[iwantreefs]

Hi, I’m wondering if anyone here is currently running a CO2 scrubber.

 

If so, how effective is it in increasing coral growth in your own experience?

 

I’m very curious to try it!

 

 

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[R0B]

Yes they can help... but there are a few things to consider. So first off coral growth is linked to ph. Higher ph has been proven to improve coral growth. Relating to a co2 scrubber my experience is that it's effectiveness is subject to whether you have a ph problem in the first place, and if so, what that problem exactly is. Running a calcium reactor may reduce your ph. Low alkalinity can also lead to low ph. Carbon dosing the like of vinegar also can be another reason of reduced ph. So the effectiveness of any co2 scrubber and thus the impact on coral growth could ultimately be limited by these and other factors. So after removing other ph limiting factors then a co2 scrubber will help. I personally found that a scrubber increased my ph by around 0.2 points (from 8.1-8.3 to an average of 8.3-8.4) which is quiet a big difference given ph is logarithmic scale. Corals seemed happy with the change.



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[iwantreefs]

Yes they can help... but there are a few things to consider. So first off coral growth is linked to ph. Higher ph has been proven to improve coral growth. Relating to a co2 scrubber my experience is that it's effectiveness is subject to whether you have a ph problem in the first place, and if so, what that problem exactly is. Running a calcium reactor may reduce your ph. Low alkalinity can also lead to low ph. Carbon dosing the like of vinegar also can be another reason of reduced ph. So the effectiveness of any co2 scrubber and thus the impact on coral growth could ultimately be limited by these and other factors. So after removing other ph limiting factors then a co2 scrubber will help. I personally found that a scrubber increased my ph by around 0.2 points (from 8.1-8.3 to an average of 8.3-8.4) which is quiet a big difference given ph is logarithmic scale. Corals seemed happy with the change.



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Thank you for the valuable input!

I have yet to perform a pH test. But I would assume it’s on the lower end of the spectrum since my alkalinity has been at the Relatively Low for the past month between 7.6dkh-7.9dkh in my nano tank.

All of my zoas are looking good and popping heads, however they are growing at a relatively slow pace in comparison to my other system.

Besides my biweekly water changes and daily feedings, there’s no other form of nutrient import into the system. And I’d much rather take a more hands off approach to maximise growth, hence I am looking at alternatives besides dosing.

I’m guessing it’s time to get a pH meter haha to see if I have a pH problem!

Is it possible for you to share the amount of soda lime you used, the rate it’s being expended and how it’s being implemented?

Thanks for the help again!


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[R0B]

I used about 1.5 to 2L of soda lime and it lasted around 3 weeks. In my opinion it ate media hahaha (even if I used damp air technique).

In all honesty I moved off traditional scrubbing media sometime back as was too costly (for me). I found running a simple airline hose through a carbon filter from outside and into my skimmer worked well. I further added an additional skimmer for the sole purpose of increasing surface area and thus gas exchange (bubbles produce loads of surface area) worked well enough and it meant I wasn't reliant on obtaining the costly media. Note. The second skimmer is not set up to skim btw, just produce bubbles. This also had the impact of increasing my dissolved oxygen levels. Which I found to be of benefit.


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[peedeers]

If you have problem with PH first you need to check if the water in your tank is fully aerated. If the co2 in the surrounding air is high then even if your tank water is at equilibrium with the air outside, the levels of carbonic acid in the water will be high, which means more fre H+ leading to highe PH.
This is rare in Singapore (unlike colder countries) we keep our windows open so the co2 levels in the air in your home should already be low (o.04 percent) almost.
In this case if you scrub the co2 using media this will bring down carbonic acid in the tank but the effects maybe only temporary till the water attains equilibrium with the air.

The other causes of ph being low is reapiration releasing co2 - eapecially at night. Or Co2 gas from your carx not diffusing into the air before getting into the tank. In thesr cases its is best to use calcium hydroxide ( kalkwasser) to supplement and remove exces co2 in the water.
Also alkalinity being low can be a cause of low PH, but in a badly awrated tank you might need to drive alk upto over 12 to reacv PH levels of 8.3.

So there is no straightforward answer as to whether co2 media has increases ph and by how much.

Since you have never measured PH best is it to start with that before thinking about boosting.



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[iwantreefs]

I used about 1.5 to 2L of soda lime and it lasted around 3 weeks. In my opinion it ate media hahaha (even if I used damp air technique).

In all honesty I moved off traditional scrubbing media sometime back as was too costly (for me). I found running a simple airline hose through a carbon filter from outside and into my skimmer worked well. I further added an additional skimmer for the sole purpose of increasing surface area and thus gas exchange (bubbles produce loads of surface area) worked well enough and it meant I wasn't reliant on obtaining the costly media. Note. The second skimmer is not set up to skim btw, just produce bubbles. This also had the impact of increasing my dissolved oxygen levels. Which I found to be of benefit.


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Wow that’s a huge level of consumption. What size system do you have ?

Has implementing the second skimmer to serve as a form of gas exchange increased the pH at the same level of a CO2 scrubber?

Thanks again for the wonderful input I shall dive deeper and seek alternatives before implementing the CO2 scrubber!


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[R0B]

My system is over 500L. My experience is that Co2 scrubbers certainly have their place (and I am currently designing and experimenting with a completely different scrubbing approach... sushhhh is secret hahaha).

My tank's ph is currently around 8.2-8.3 so is marginally less then the peak obtained when I had a scrubber. However, if I implemented a scrubber now after implementing other methods the impact would be less (although the media would last much longer). So the order you implement various solutions also impacts their individual benefit.

Good luck



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[JiaEn]

On 4/7/2021 at 8:51 AM, R0B said:

This also had the impact of increasing my dissolved oxygen levels.

When I installed a DO probe to monitor the variation of DO in the aquarium,  the results was rather interesting. 

When the skimmer is on at night,  it does increase the DO as expected. But having the skimmer on during light hours, actually lowers the DO. 

 

[JiaEn]

/accidentally posted

Just now, JiaEn said:

having the skimmer on during light hours, actually lowers the DO. 

This actually make sense because our reef becomes supeesaturated due to photosynthesis. So perhaps additional skimmer for gaseous exchange is not needed/counter productive during day light hours. 

[R0B]

/accidentally posted
This actually make sense because our reef becomes supeesaturated due to photosynthesis. So perhaps additional skimmer for gaseous exchange is not needed/counter productive during day light hours. 

This is a really interesting result, as in the wild coral reefs record some of the highest levels of DO (upto 200% 15+ ml) because of a combination of photosynthesis and increased aeration from eddies and breaking waves. What you are suggesting is that aeration via a skimmer actually lowers the DO. Whilst I have observed between fluctuations between 100% and 150% on my own tank I have never seen a case where a skimmer reduces DO. But what I love about this hobby is the opportunity to learn something new. Will PM you...



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[peedeers]

I think both of you are saying the same thing. People tend to perceive the skimmer as a mechanism to inject O2 into the water. Thats not true. A skimmer enables additional gas exchange so that the chemical potential of O2 or co2 in the air intake is same as that of the dissolved gases in the water. So it is tending towards equilibrium. So if O2 is higher in the intake air, then it will appear as though the skimmer is reducing DO in the water.


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[peedeers]

I think both of you are saying the same thing. People tend to perceive the skimmer as a mechanism to inject O2 into the water. Thats not true. A skimmer enables additional gas exchange so that the chemical potential of O2 or co2 in the air intake is same as that of the dissolved gases in the water. So it is tending towards equilibrium. So if O2 is higher in the intake air, then it will appear as though the skimmer is reducing DO in the water.


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I meant if o2 is lower in the air intake.. in my last sentence.


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[JiaEn]

22 minutes ago, peedeers said:

I think both of you are saying the same thing.

Yes. @ROB We meant the same thing.  

 

50 minutes ago, R0B said:

I have never seen a case where a skimmer reduces DO

Just like @peedeers said,  the skimmer shifts the aquarium water towards an equilibrium with the environment air. So for massively oversaturated dissolves oxygen level,  skimmer will bring them down somewhat. 

[src]

The c02 scrubber works for me, which mange to bring up 1-2 ph point. But the effect is limited, if you are trying to bring up 7.8 to 8.3 then you will need to combine with other methods as well.

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