Re: Aquatic Plants Digest V1 #262
Just a few comments on the pH electrode. It will probably prove to be
impossible to find an electrode that does not have a "Calomel" reference
cell in it (that is the bit with the silver). It is used to give the
signal that allows the electrode to work. The electrodes use a special
glass that only allows H+ ions accross and this is reduced by the
platinum elctrode in the probe itself, the difference between the
reference elcetrode and the platinum one is what gives rise to the value
on your meter.
In one pf my planted tanks I noted a .6-.7 pH shift from the time that
the lights came on till they went off. This was in my pre CO2 days.
Sunny warm Canberra Australia.