Confused- please help


New member
I'm confused about calcium reactors vs kalk stirrer's... I know how they both work and the concept behind them but I guess I'm not sure of the chemistry behind them.

I understand that in a reactor the co2 mixes with the water in the chamber to make the ph fall (6.5 - 6.9ish range) then dissolves the media in the chamber; from there drips into the tank replenishing calcium(or alk?)

In a stirrer fresh water is mixed with kalkwasser to create a highly alkaline liquid and the powder at the bottom stays agitated while the 'milky water' at the top gets dripped into the sump. The ph of this liquid is somewhere in the 12.xx range?

So I guess from what I know, why would one use both in a system? Is one better than the other? I have run a calcium reactor but never a stirrer.

Sorry if this is in the wrong forum! (could a mod please move to the correct forum if not?)

Henry Bowman

Reefing since '87
The reason most folks run both is because Calcium reactors have a tendency to lower pH and KalkReactors have a tendency to raise pH....counteracting the lower pH of the CaRx.
Along with what has been mentioned above, economics will come into play for many hobbyists. The cheapest way to maintain your alk and calcium will be using kalk water as long as it meets your demand. The next cheapest will be a kalk reactor as long as it meets your demand. The calcium reactor will supply the most alk and calcium, but will reduce your pH and is the most expensive & complicated. Some hobbyists run all three two meet their demand and also dose two-part. ;)

Randy's article goes into more details regarding which method may be most appropriate for your situation:

How to Select a Calcium and Alkalinity Supplementation Scheme

Henry Bowman

Reefing since '87
I run 2 part on a doser. The good dosing units will cost as much as a CaRx. I had a reactor and didnt like the pH hassle. Now I have a pH in the 8.3 range that doesnt go lower than 8.2 at night since I dose the alk portion (increases pH) in the middle of the night.