Solenoid Valve / pH Control
A solenoid is simply an electrically operated
valve. When electricity is supplied to the valve, it opens,
and when the electricity is off, it closes. Its possible uses
are as follows:
The simplest and most common way to utilize
a solenoid is to plumb it into the line between the CO2
bottle and the calcium reactor. In the event of a power outage,
the CO2 flow is switched off, stopping
any gas escaping from the calcium reactor into the tank.
A more elaborate method is to connect the
solenoid valve to a pH controller and place the pH probe into
the calcium reactor. The valve then switches the CO2
on and off to maintain a target pH within the reactor. I use
a similar method. The pH probe is placed in the tank, and
switches off the CO2 flow to the calcium
reactor only when the pH in the tank has dropped too low (e.g.
pH 7.8 or lower).