CO2 scrubbers & reactors; why?

[MPS]

I’d like a little education please. There are products on the market to remove CO2 from the water (chemical scrubbers) in order to raise PH. I use one of these on my skimmer inlet. Then here are products on the market that inject CO2 into the water (CO2 reactors). When is it good to add CO2 rather then scrub it out?

 

[Waters]

I’d like a little education please. There are products on the market to remove CO2 from the water (chemical scrubbers) in order to raise PH. I use one of these on my skimmer inlet. Then here are products on the market that inject CO2 into the water (CO2 reactors). When is it good to add CO2 rather then scrub it out?

I believe it is used for the same reasons it is used in freshwater planted tanks.....to provide plant growth. In a reef, to provide "fuel" for zooxanthellae. The issue becomes balancing the lowering PH and ALK though.

 

[Realposition]

Ive never heard of anyone injecting CO2 outside of when using a calcium reactor. CO2 is injected into a calcium reactor to lower the PH in the reactor and melt the media.

 

[Gareth elliott]

Co2 injecting is a freshwater planted needed equipment.

Photosynthesis requires co2. At the ph and alkalinity we keep our reef tanks this comes from the carbonate.

In a low ph, low dkh planted aquarium co2 is often deficient and without injecting co2 plants die off and algae grows, once you leave low light setups anyway.

This switches on with my lights and goes to a bubble counter than a ceramic diffuser. I inject to maintain around 30ppm co2 during the photo period.

 

[Michael Llabona]

CO2 scrubber to raise pH. Some peoples tanks run at 7.8 or less. BRS has a video where maintaining a higher pH (8.3, also assuming all other parameters are consistent) resulted in faster coral growth.. like 25-50% faster growth. You only use a CO2 reactor on a reef tank if you have a calcium reactor.

 

[MPS]

Thank you everyone for your quick reply. This now makes perfect sense.

 

[Randy Holmes-Farley Verified Community Expert]

I've actually never heard of anyone needing (or using) actual CO2 addition to a reef tank. More ordinary aeration will always solve any high pH low CO2 issues, such as comes with dosing limewater or extremely high levels of photosynthesis.

CO2 is not in short supply in a reef tank as it is in fresh water tanks because many reef organisms get CO2 from bicarbonate, which is relatively plentiful. Adding extra CO2 lowers ph, and while that may help certain photosynthetic organisms, it hurts hard corals and other calcifying organisms.