For normal operation, the recirculation speed of the pump should be
set so that the fine bubbles pass down the gas chamber and then return
to the surface of the gas pocket.
The lower level should be carefully set so that you can still see the
central suction pipe and observe that very few bubbles are passing over
into the media chamber.
It is not necessary to have the fine bubble rate too low for normal
operation as this will use a little more gas as the bubbles pass into the
media chamber.
Note that water chemistry changes can also have an effect on how far
down the bubbles travel and some days you may see changes in the
level without and adjustment of the recirculation rate.
Measuring the pH within the reactor
It is absolutely not necessary to measure the pH within the reactor as it is not used for control, however it
does allow you to understand what is going on as you make small adjustments.
Generally, throughout the day there will be a small rise in pH between degas cycles due to the build-up of
inert gas released from the media.
On the chart below you can see the initial rapid drop from normal tank pH as the reactor is first switched on
and the 2 peaks B & C, just before each degas cycle.
Overdriving the reactor:
It is also possible to overdrive the circulation rate so that the bubbles are forced
down even lower than for the normal running level. In this method, small amounts of fine bubbles are
continuously drawn into the central suction pipe and out into the media chamber.
The small amount of lost gas is continuously replaced with fresh CO2, thus preventing build-up of the inert or
non-reactive gas from the dissolving media within the gas pocket.
This can be observed in the graph above after point C where you can see a constant LOW pH and you would
also measure a corresponding higher dKH from the reactor. The pH is then running at a constant 5.8.
Use in this format will allow you to extend the period between normal degas cycles but may also increase
the amount of CO2 used.
Normally it is only necessary to run the reactor this hard if you nearing its maximum output capacity for your
particular aquarium. It is also likely to result in a generally lower pH within the system.