I have controllers for both of my calcium reactors and still do it manually and just use the controller as a monitor. Jeezz one of these days I am going to have to hook them up. I will monitor the effluent - my gro-tech calcium reactor has a port to insert the PH probe right into the body of the reactor to get a really accurate reading too!

#1 for me, I usaly adjust bubble and flow to get my output Alk about 3X higher than my desired tank Alk, then after that I just adjust the flow through the reactor to fine tune the tank Alk.

Steve

similar method but I shoot for a Ph of 6.7-6.9 then adjust the effluent rate to control the tank ALK

If you want your alk to be about 10 in the display tank, how do you measure effluent with an alk of 30 when the test kit charts only go half that? Do you just keep adding more reagant and continue to follow the same scale?

Use a titration based test kit (i.e., add drops until you get a colour change) instead of one with a colour comparison chart ("is this shade of green more like this yellow-green or more like that green-yellow?"). Seachem and Salifert are both titration based for alk.

Good info everyone, thanks.

If you do go with a PH controller, IMO, the best way to do it is set the controller to the tanks PH , ie: to shut off at 8 PH
Remember the idea of the controller is to protect the tank and it's inhabitants.
That is how I have mine set up anyways

break your test sample into 1/2. so if your unit calls for 4ml of tank water, you put 2ml in and then 2ml of pure RODI water (I use distilled when I do this) I have even gone as far as using 1/4 of the sample. I usaly go for a Alk of 13 so I am looking at 39 as a measurment.

Steve