I just use the cheapie (BRS type) dosers. They can only go off and on, and must be controlled either by a timer or a controller. I use two of them for my alk and Ca and are controlled by my Apex. I have a spare one, in case one of them craps out. But I don't see a need for a 3rd, as I manually dose my Mg with my water change every 3 weeks.
I like to control as much as I can through my Apex, as it is easier to do on my computer (or remotely through the internet), and easier to monitor. And I don't have to worry about power outages and resetting any timings.
|