The ph needed to 'melt' the media will depend on the media used , typically
though an internal reactor Ph of between 6.1 - 6.5 will be required.
There are two key reactor settings that will need adjusting to tune the reactor
and to maintain your systems demand for Calcium and Alkalinity.
When setting up the reactor you will only need to test the effluent for Alkalinity
as the reactor will produce Alkalinity and Calcium in balance. Therefore
there is no need to check the effluent for Calcium if the reactor is producing
the required levels of Alkalinity.
To tune the reactor for best performance you first need to set the effluent
rate. I suggest starting out with a slow drip rate of around 1 drop every
two seconds (30 drops a minute) .Once the reactor is set up this can be
increased to match the demand of the tank. If using a fixed peristaltic pump
ensure that it is rated correctly for the reactor .
If the peristaltic pump specified or effluent output rate is set higher than
the maximum working capacity of the calcium reactor you will find that the
effluent Alkalinity (dkh ) will drop even if setting a very low Ph within
the reactor or high bubble rate. This is due to the contact time within the
reactor being too short for the capacity of media it can hold.
Internal Ph/bubble rate:
Once the initial effluent rate has been set we need to look at the CO2
bubble rate and if using a Ph controller the internal Ph of the reactor.
If using a feed pump/variable drip rate set CO2 rate at a count of around twice
that of the effluent drip rate, after leaving the reactor running for at
least an hour check the effluent Alkalinity using an aquarium test kit
(Salifert kit in low range mode is quite accurate). You are aiming for an
effluent dkh of between 35-50dkh, if the effluent dkh is low increase the
bubble rate slightly and test an hour later. Continue to do this until the
target dkh is reached. This will be the optimum output for the reactor at the
drip rate set.
If using a ph controller then set this initially to switch the C02 supply
solenoid off at a ph of 6.5, adjust the CO2 bubble count to around 30
bubbles per minute to begin with. Leave this for two hours then check the controller
display, the ph inside the reactor should have dropped down to the desired ph i.e.
6.5. If you find the ph has not dropped sufficiently slowly increase the
bubble rate leaving an hour between each adjustment until the Ph has dropped
to that set on the controller.
Calcium reactors work best with a steady constant supply of CO2 so don't be
tempted to crank up the bubble rate to reduce the ph quickly, this will
result in the solenoid cycling on and off over short periods and possibly
causing excess CO2 to build up in the reactor.
Once the desired Ph has been reached check the effluent Alkalinity, the
ideal Alkalinity should be between 35-50dkh. If the effluent Alkalinity is
low drop the controllers Ph by 0.1 and leave for an hour and check the
effluent dkh again. You may find you have to increase the bubble rate with
each adjustment of the controller to achieve the new Ph limit set, this is
When you find the effluent dkh is between 35-50dkh your controller will be
set at the correct Ph required to 'melt' your media. Remember to calibrate
your Ph probe before set up!!!
Once the reactor has been set up to achieve the optimum effluent alkalinity
you will need to tune the reactor for system demand. With the reactor
running check your systems alkalinity, write down the results and check the
systems alkalinity again 24 hours later. If your systems alkalinity has
dropped you will need to increase the output of the reactor to match demand.
If using a feed pump adjust the effluent rate via the red control tap on the
reactor ,you should aim to increase the output by around 25% from the base
setting above. After an hour test the effluent dkh, if you find that
effluent dkh has dropped increase the bubble rate to achieve the correct
Check the aquarium alkalinity again 24 hours later and if
needed follow the steps above to increase the reactors output again. Repeat
these steps until you find the aquariums Alkalinity and Calcium demands are
being met by the reactor
If using a fixed peristaltic pump you can attempt to increase the reactors
output dkh into its upper levels by increasing the bubble count, don't try and
force the effluent dkh up too high though as this may result in the Media
turning into a mush and CO2 building up in the reactor.
If using a Ph controller you may wish to reduce the ph in the reactor in an
attempt push up the effluent dkh, an internal ph of under 6.1 may result in
gas building with the reactor and the media breaking down and
Its important to test the Aquariums alkalinity 24 hours after any adjustment
so demand can monitored and the reactor adjusted to suit as above
It is advisable to only run the CO2 via a solenoid during the day and turn
it off during the night, this is because the effluent from the reactor has a
During the day your aquarium ph will be higher due to coral/algae
respiration within the aquarium. At night the Ph will drop naturally and the
reactor effluent may pull the aquarium Ph down even further to undesirable
levels, so depending on the Ph stability of your system you may want to turn
the CO2 off during the night and run it slightly harder during the day.
Monitor the Ph swing of the aquarium and if the Ph swings by more than
0.2-0.3 during a 24 hour period it would be advisable to only run the
Calcium reactor CO2 supply during the day.
As an extra measure the use of a Kalkwasser stirrer that is set to dose
during the night will help stabilise Ph and add Calcium and Alkalinity
to the system.
If you make adjustments to increase the effluent rates you will need to make
appropriate adjustments to the CO2 rate to maintain effluent alkalinity
Set the internal Ph of the reactor to give the desired effluent Alkalinity,
this will be the optimum Ph for your media
Set the effluent flow rate and effluent dkh to keep up with system demand,
if the system Alkalinity increases then decrease the effluent amount and/or
the effluent dkh via the bubble count (internal reactor Ph) and visa versa.
Always specify the correct size calcium reactor for the aquarium, when you
reach the maximum effluent rate for the reactor the effluent dkh will drop
regardless of Ph or CO2 input. Its better to over spec a reactor and run it
at half duty if needs be than choose one that’s too small and struggle with it.
Decrease the on time of the C02 solenoid via a timer if you wish to turn off
the CO2 supply at night to reduce Ph swings.
Adjust the CO2 count as low as possible to achieve the desired reactor Ph if
using a controller to prevent frequent on/off cycling of the solenoid
Leave at least an hour after adjusting the reactor to test effluent dkh
Don't attempt to throttle the effluent back via the red control tap if using
a Peristaltic pump, this will damage the pump. Keep the tap open at all
Always leave the reactor feed pump and recirc pump running.
Make sure all CO2 fittings aren't leaking and a non return valve is in place
to stop tank water entering the solenoid.