Single vs Dual Chamber calcium reactor

91Reefer · Sep 17, 2026

Hey all, Am planning to add a calcium reactor for a sps dominated 150 gallon tank and want to know you thoughts on a single chamber vs dual chamber calrx

KrisReef · Sep 17, 2026

I have not used one, so I cannot attest to the suggested performance improvement one might gain by having the second chamber.
I have used different sized reactors, and if they are too small for a system's demands you have to buy a bigger one. They have a limit to how much aragonite can be dissolved into solution.

SO, the amount of coral you are trying to keep alk'ed will determine how much cylinder capacity you will need. Larger cylinders provide surface area for large flow through at low pH to dissolve the media. Having extra media is not a problem, but having too small a reactor with large demand is where a second cylinder is needed.

Imagine you have a reactor the size of your DT- Probably too big. Hope this word illustration is helpful?

The Farmer · Sep 17, 2026

Second chamber is for co2 gas off, it helps it not lower your tank ph. Also helps with the effluent preventing over working your calcium reactor.

The Wannabe Reefer · Sep 17, 2026

FishOHex on YouTube has a couple of videos confirming that a secondary chamber does increase pH, but only slightly. The question is, do you want to spend all that money on a secondary chamber for such a small increase in the PH? I recently added a calcium reactor and instead went with the GEO Super Silence Extreme, which uses the secondary chamber to use more of the Co2 (95%).

MIKE NY · Sep 17, 2026

I’ve been running a two chambered for years. For me It definitely helps. Every system is different, but to maintain the Alk demand in my heavily stocked system the first chamber runs at 6.6 and the effluent out of the second is 7.0. I top off the first about every 5-6 months and the second maybe every year or so.
BTW …I use Reborn media.

91Reefer · Sep 17, 2026

MIKE NY said:
I’ve been running a two chambered for years. For me It definitely helps. Every system is different, but to maintain the Alk demand in my heavily stocked system the first chamber runs at 6.6 and the effluent out of the second is 7.0. I top off the first about every 5-6 months and the second maybe every year or so.
BTW …I use Reborn media.

How good is the reborn media heard they leach a lot of po4 .

91Reefer · Sep 17, 2026

The Wannabe Reefer said:
FishOHex on YouTube has a couple of videos confirming that a secondary chamber does increase pH, but only slightly. The question is, do you want to spend all that money on a secondary chamber for such a small increase in the PH? I recently added a calcium reactor and instead went with the GEO Super Silence Extreme, which uses the secondary chamber to use more of the Co2 (95%).

Super useful video