Soft pond water, having a JH value (= calcium and magnesium hardness, also referred to
as total hardness, expressed in GH) lower than JH 5 °GH can easily become acid.
Continuous rainfall will intensify this process. Especially in autumn and winter this can
result in death of fish. Also the growth and development of oxygen producing plants (like
hornwort, waterweed and pond weed) will be inhibited at a too low JH value.
A healthy and stable pond environment has a total hardness ranging from JH 8 to 12 °GH.
Regular inspection (4 to 5 times a year) of the JH value is therefore desired. If the value
will decrease below JH 7 °GH, measures have to be taken. With the help of Velda GH Plus
the total hardness can be increased without any problem.