19
=8
valve to “man open“: Menu key > select valve > press OK > with selection keys select “man
open“> press OK. For
u
403 continue as for
u
401 and for
m
603 /
m
1003, as for
m
601. After
the reactor has run in, set the integral solenoid valve to “auto“: Menu key > select valve >
press OK > with selection keys select “auto“> press OK. Then set the optimum pH level for
your aquarium and the required number of bubbles on the pH computer as described in the
instructions for use enclosed separately. The pH computer now automatically regulates
the pH level and the CO
2
supply for your aquarium.
13 How much CO
2
is needed?
13.1 pH level, CO
2
and carbonate hardness (CH)
The three parameters, pH value, CO
2
content and carbonate hardness are inseparably linked,
as they are interdependent.
When CO
2
comes into contact with water, a certain amount of carbon dioxide is produced which
reduces the pH value. The greater proportion remains dissolved in the water in the form of gas
and serves as an important nutrient for plants. Therefore CO
2
has two benefits: it reduces the
level of pH in the aquarium, which is usually too high, to a level conducive to fish and plants
whilst at the same time providing plants with their main source of nutrient. Thus luxuriant plant
growth and lively, healthy fish are guaranteed.
How much CO
2
is needed to maintain a particular pH value depends on the CH in the aquarium.
The higher the CH, the more CO
2
is required. Once the CH and pH values are known, the CO
2
content can be calculated. The following table saves you making the calculations and also
shows the pH values which you can set as an optimum value without any risk to your fish.
CO
2
content depending on pH value and CH
Too much CO
(
CO
(
correct
Too little CO
(
auto pH curve
