Just grow it: Have you ever added CO2 to your reef tank?

[Peace River]

Just grow it: Have you ever added CO2 to your reef tank?

There are many reasons to use CO2 (i.e., carbon dioxide) in a reef tank including for promotion of calcium carbonate production, increasing macro algae growth, enhancing coral growth, providing algae control, and optimizing pH regulation. While CO2 has long been commonly used for growing freshwater aquarium plants (especially in high tech planted tanks), CO2 seems to not be used as commonly in reef tanks despite the wide array of benefits. What about you – have you ever added CO2 to your reef tank? Are there specific things that have held you back from adding CO2? If you have used CO2, please let us know what you used it for and please share any best practices or recommendations. Also, we’d love to see pictures of your CO2 setup!

Photo by @X-37B


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[dadnjesse]

Anyone with a calcium reactor is using C02

 

[Acroporaguy]

Aside from a calcium reactor I don't see any practical usage of CO2 on a reef tank given the negative relationship it has with pH.

 

[shakacuz]

don't use a carx. so no :/

 

[Dburr1014]

Just with my calcium reactor.

Most reefers trying to get it out not in.

 

[Beta reefs.]

It helps plants and algae grow better, so maybe to speed macro growth

 

[MattPLaw]

I am actively trying to remove excess co2 by using a co2 scrubber on my skimmer air intake. I think whatever benefits it may have are out waid for me by the significant drop in ph I see when I have too much co2.

 

[helmsreef]

Other than using it for my calx I dont see any other use for it in a reef system.

 

[Fish Styx]

I use CO2 in my CaRx

 

[Sisterlimonpot]

With conversations being that pH is a major player in stony coral growth, I don't think there would be any benefit to dosing c02 just to promote macro algae growth.

Perhaps carx are now considered a fringe way to introduce/maintaining major elements, it's the only thing that one would use c02 on a reef tank.

 

[Garf]

Yes, I added CO2 to an algae scrubber. Increased mass tremendously. Its a bit scary though, with limited control from a yeast culture/thingy. I stopped after a month or 2.

 

[darrick001]

Unless your ph is over 8.49 I wouldn't see any reason for it. If it's only for algae growth just add an air stone into your refugium. Your skimmer already adds co2 if the levels are lower than they are in the air. If you don't take any action to raise ph it will normally stabilize around 7.8. According to some research I read coral growth stops below 7.8. I can't remember the article, but BRS did a nice video on ph and coral growth. They quoted the article there.

 

[ShakeyGizzard]

had 2 tanks running with my freshwater set ups , but not needed unless aquascaping with plants. I see PH issues in my future and plan on limiting CO2 in my saltwater tank. Would hate to have to dose to bring it up with LPS.

 

[Sdot]

Unless your ph is over 8.49 I wouldn't see any reason for it. If it's only for algae growth just add an air stone into your refugium. Your skimmer already adds co2 if the levels are lower than they are in the air. If you don't take any action to raise ph it will normally stabilize around 7.8. According to some research I read coral growth stops below 7.8. I can't remember the article, but BRS did a nice video on ph and coral growth. They quoted the article there.

Skimmer adding co2!? Lucy you go some "eh plaining to do" lol

 

[ChrisH]

I have a high pH problem. Easy to say that the readings are wrong to give a consistent 8.7 to 8.8 (I have both Apex, test kit and Seneye - even sent back the Seneye device for checking and replaced it) and all agree. Softies seem happy, hard coral less so, fish fine ... But I have struggled to get this down. Calcium reactor uses CO2 - so would it be an advantage to feed gas directly into the skimmer as well? Or, what other solution?

 

[Garf]

I have a high pH problem. Easy to say that the readings are wrong to give a consistent 8.7 to 8.8 (I have both Apex, test kit and Seneye - even sent back the Seneye device for checking and replaced it) and all agree. Softies seem happy, hard coral less so, fish fine ... But I have struggled to get this down. Calcium reactor uses CO2 - so would it be an advantage to feed gas directly into the skimmer as well? Or, what other solution?

Are you adding any high pH additives?

 

[darrick001]

Wow over 8.7. I've only seen that with over dosed additives or with a refugium running very intense lighting for extended periods. I can get mine that high but try to keep it below 8.49. If I had a skimmer running I would not be able to keep it that high. Explain your system setup equipment your using, every thing you add. I don't know what could be causing it without your system information. With the fact your running a skimner and a calcium reactor I don't think adding more co2 will help your system.

 

[darrick001]

Skimmer adding co2!? Lucy you go some "eh plaining to do" lol

Yes a skimmer will add co2 if the levels in the air are higher than in the water.

 

[darrick001]

I have a high pH problem. Easy to say that the readings are wrong to give a consistent 8.7 to 8.8 (I have both Apex, test kit and Seneye - even sent back the Seneye device for checking and replaced it) and all agree. Softies seem happy, hard coral less so, fish fine ... But I have struggled to get this down. Calcium reactor uses CO2 - so would it be an advantage to feed gas directly into the skimmer as well? Or, what other solution?

I did a little research. As long as your not dosing to much and the PH is not swinging wildly, your higher than normal ph isn't a big deal. If your dkh is high than something your dosing is probably causing it. With a skimmer, and co2 reactor running its very unlikely your co2 is to low as both add co2 to your water. A Skimmer only adds co2, if co2 in the air is at a higher concentration than it is in the water. This is all assuming your not using a co2 reactor on your skimmer air intake.

 

[ChrisH]

More info then (thanks for the responses).

The system is two identical aquaria, one display and one as a sump in the garage below (two pumps return water through the floor) amounting to 1,000 litres capacity (so around 900 litres of water). Calcium reactor running on its own, not via the Red Sea skimmer. Alkalinity about right, calcium perhaps a little high, phosphate a bit low, nitrate a little high sometimes, but all in the right sort of area (I have trouble maintaining phosphate above zero). Dosing is limited to alkalinity. Other kit is limited to a Red Sea roller mat.

Context: I've kept a reef for about forty years now, through two houses and two catastrophic failures (one from the front glass springing a major leak and the other from the power tripping while on holiday; the first allowed time to save about half the contents, the second virtually nothing survived). In that sense, the current setup is about four years old, being restocked with new water, sand etc.

It is possible that CO2 in the air is no more than normal %, in that the skimmer and sump are in the garage and isolated from what might otherwise be sources of any increase. The display is in a large open plan area so plenty of air and I think unlikely, given the floor plan, much chance of building a high CO2 level.

But the pH does not swing much; according to the probes, no more than 0.2 day/night (less than I would have expected, really).