The Kalkwasser mixer can be positioned inside or outside of the sump or stood inside the freshwater reservoir as long as the distance from the outlet to the point of introduction to the system is not too far.

Add approximately 1.5 inches of calcium hydroxide powder to the empty mixer body and fill the to ¾ full with fresh water stirring manually to partially dissolve. Alternatively fill the vessel first and spoon in the powder, stirring with each addition. Put the stirrer lid, motor and stirrer rod in position by mating the grove on the lid with the top of the stirrer body. Site the unit and plug the transformer into the mains, the rod should now be turning. Leave the mixer running until the top of the solution starts to clear. This prevents undissolved calcium hydroxide from entering the aquarium.


1. - Care should be taken not to breath in the fine calcium hydroxide dust and also with the freshly mixed solution as it is caustic and will dissolve clothing or similar items. If you have prolonged contact with your skin or get any in your eyes flush well with copious quantities of fresh water.

2. - The transformer supplied is fitted with a variable output. This is factory set and should not be operated above 7.5V.

Connect the fresh water supply tube to the inlet control tap which should be closed. Open the valve carefully to allow the water level to rise slowly within the mixer. Once the solution starts to exit from the outlet nozzle adjust the tap until the flow is reduced to a slow drip which should enter the tank in a position of strong flow to allow rapid dispersion. It is possible to extend the outlet with a suitable length of hose however care should be taken that the hose runs downhill to prevent the solution from standing and being exposed to CO2 between additions.

It is very important that fresh Kalkwasser is added drop wise as too high a flow rate can cause a localised calcium concentration, which, if high enough, can drop the calcium out of solution. High flow rates may also raise the pH too quickly within the aquarium.


The Kalkwasser stirrer should stir the solution continuously 24-7 however it is possible to experiment with additions of Kalkwasser outside of the aquarium photoperiod, i.e. at night, to reduce the drop in pH which naturally occurs when photosynthesis stops. This is achieved by installing a timer on the supply prior to the water supply.

The Deltec Kalkwasser Stirrer can be operated in combination with the Deltec Calcium Reactor with positive effects as Kalkwasser compensates for the excess of bicarbonate from the calcium reactor through additional calcium supply.

Acids which are continuously produced in the marine aquaria are neutralized by kalkwasser and the carbonate hardness is stabilised.

An excessive increase in the pH value is avoided by slow addition of the solution via an automatic (top-up system) supply.