Why do you need a CO2 diffuser with a Ca reactor?


New member
Title basically says it all. I hear that if you have a calcium reactor, you need a CO2 reactor to balance something out (Not exactly sure what) or else you will get a ph spike. Can someone explain this chemically? Thanks.


u need co2 to disolve media into the efluent fluid the regulator and solenoid control co2 so u dont dose to much co2 into your dt and have a massive ph drop. most common recommended is balancing your ph at 6.5 in reactor


ReefKeeping Mag staff
Premium Member
I don't uderstand your question. Do you mean a kalk reactor used in conjunction with a calcium reactor?


New member
the CO2 is what creates the calcium. CO2 tank is controlled by a solenoid and a regulator. When CO2 is combined with saltwater, it creates carbonic acid. The carbonic acid which is circulated through the reactor full of crushed coral, breaks down the crushed coral thence releasing calcium (what coral is made of). Its best to have a Kalk reactor also because the CO2 lowers the Ph. To counter this, kalk is used which has a Ph of around 12. My Kalk is implemented in with my ATO.



Premium Member
The carbon dioxide dissolves the calcium carbonate in the media, releasing ionic calcium and carbonate (alkalinity). The carbonic acid can tend to lower the pH a bit, but some people don't find that to be a problem. Limewater can help if the tank's pH is a bit low.