Kalk Stirer

What is a Kalk stirrer?

This piece of equipment is connected to your top-up unit that tops up with RO water.

As you can see in the picture the long column is filled with RO water from your top-up and into this you add 1 teaspoon of calcium hydroxide powder (Kalkwasser). This column is designed to be air tight. If air is allowed into the column it reduces the efficiency of the Kalkwasser being dosed into the tank, which defeats the purpose of adding Kalkwasser which is for the purpose of maintaining the pH, alkalinity and calcium levels in the tank.

The Kalk reactor can either be used on its own or in conjunction with a calcium reactor. In large systems I have found using a Kalk stirrer with a calcium reactor works far better as they work hand in hand with each other maintaining pH, alkalinity and calcium. Kalk stirrers only work in a system where the tank is losing enough water through evaporation taking place, to dose enough Kalkwasser to the system to maintain pH, alkalinity and calcium. The only way to find out whether the Kalk stirrer is sustaining the water parameters is to check pH, alkalinity and calcium for a couple of weeks. Once assessed as to what the water parameters are, one can then make the decision as to whether a calcium reactor may be needed or not. In the event of the water parameters still reading low one then has no option but to add a calcium reactor to maintain these water parameters.

One thing that must be remembered when dosing with calcium hydroxide through a Kalk stirrer or any other means the pH and alkalinity must be monitored carefully due to the pH of calcium hydroxide being at a pH of 12 whereas the normal pH of a marine tank is 8.3. The same thing is said for monitoring carefully alkalinity and calcium.

In tanks fewer than 500 L a Kalk stirrer does not work efficiently enough to maintain these water parameters due to there not being enough evaporation for the top-up to dose enough RO water through the Kalk stirrer to maintain the pH, alkalinity and calcium. There is no option then, but to manually add extra calcium, alkalinity buff, or pH to maintain the various water parameters required.

I hope this has shed more light on what the Kalk stirrer does.