Pros vs Cons: Calcium Reactor vs Kalkwasser Reactor Quick Run Down: Calcium Reactor: A calcium reactor uses crushed coral, or calcium reactor media (which is made up of dead coral) and dissolves it into the reactor using Co2. The Co2 lowers the PH inside of the reactor dissolving the crushed coral. This out flow is called the effluent and has a very high amount of calcium and hardness (alkalinity). You will dose this in your tank at a constant rate to keep your levels up. Kalk Reactor: The kalk reactor uses basically a pickling lime, or kalkwasser to do some what the same thing. But this is done via auto top off or some sort of doser and includes much more maintenance. A kalk reactor is a holding device that mixes up the kalkwasser with the water. Then at set times you dose this in your tank. So in your opinion what are the pros and cons of each of these reactors?