Aqua Medic CO2 Box, Operation Manual

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11
The Aqua Medic CO
2
indicator is used to determine the carbon dioxide content of the water in a
simple way. Carbon dioxide is a very important nutrient for healthy plant growth. At the same
time, this quite good water-soluble gas is toxic to the animal life in the aquarium in high
concentrations so that a check of the available quantity is extremely important.
Please shake the indicator’s fluid before use.
Take off the white lower part with the sucker and fill in max. 1 ml of indicator dissolution into the
transparent vessel. If you take less dissolution, the test shows faster reaction times and is still
easily readable. Remount the lower part and mount the permanent test with the transparent cover
up to an aquarium pane. Cover the sucker from the outside of the aquarium pane with the included
colour scale.
A blue colour indicates too little carbon dioxide, a pale green to yellowish indicates too much
carbon dioxide. A dark green colour (see indicator disc) shows that the content is okay. If the
colour fades in the permanent test, the unit must be refilled.
Warning: The carbon dioxide gets from the water into the air by diffusion and from the air back
into the test liquid. Therefore, it can take some time until the right colour is displayed.
Raising the carbonate hardness (alcalinity)
Aquarium water should have a minimum carbonate hardness of 4 – 6 °KH (1.5 – 2 mmol/l). Below
this limit, the pH of the water cannot be stabilized. Biological processes produce permanently
organic acids that reduce the carbonate hardness. Filtration with peat or the use of other acids
(Phosphoric acid or hydrochloric acid). If peat products are used for filtration, the carbonate
hardness of the water should be checked weekly. If the KH drops below 4° in fresh water or 6 ° in
salt water, it should be raised. We recommend Aqua Medic aqua+ KH.
The optimum CO
2
quantity
The quantity of CO
2
that can be dissolved in water depends on the carbonate hardness (alcalinity)
and the pH-value of the water. The higher the carbonate hardness, the higher is the CO
2-
concentration – at the same pH-value. But high levels of carbon dioxide can lead to suffocation of
fish and other marine life.
Table 1: Dependence of the carbon dioxide concentration of carbonate hardness (KH) and pH-
value. CO
2
concentrations between 10 and 35 mg/l are ideal. In the upper column, you see the pH-
value and in the left column, the carbonate hardness. The corresponding quantity of carbon dioxide
can be seen where the columns intersect. Also, you can look at the desired carbon dioxide content
and the carbonate hardness to find the corresponding pH-value in order to determine e.g. the set
value for a pH control unit.