I have combined dosing with top-off which requires far less effort on my part and also means that the tank can go for days without the need to add anything other than food for the fish and corals.

The calcium demand for the tank is reasonable and the equivalent of one to two litres of Kalkwasser per day is sufficient. One to two litres of water evaporates from the tank each day and so full strength Kalkwasser is added to the reservoir. The Kalkwasser is decanted liquid from my Bulk Kalkwasser. A sheet of polystyrene cut to the size floats on the surface of the Kalkwasser to reduce gas exchange.

The above mixture is added to the tank as required via an Aqua PER-R peristaltic pump (instead of a powerhead) connected to my Auto Top-off II control unit. The PER-R peristaltic pump has an adjustable flow rate up to 1 L/hr and I have the pump turned down so that it delivers at a rate of around 250 mL/hr. The Auto Top-off control unit is connected via a plug-in timer which is only on for 15 minutes from 8:00pm and then on for 15 minutes out of every 30 minutes between 9:00pm and 7:45am, for a total time of 5 hours, 45 minutes. This means that if I have a failure with the float switch or control unit, less than 1.5 litres per day will be delivered to the tank and this is unlikely to cause any issues.

The Kalkwasser is only dosed at night when the tank pH tends to be lower due to higher concentrations of CO₂. The extra CO₂ helps in converting the hydroxide to bicarbonate. Dosing during the day led to too high a pH.

Last updated: January 9, 2006