What pumps are you using? I think the Kamoer pumps for dairy that theatrus linked earlier are pretty dang nice.
Im going at this a different way, using the standard BRS 1.1ml / min pumps that are 120v and using the timer function to outlets. I have to add a couple outlets, calibrate and then figure it will be a run 35 second on the hour for ALK and run for 35 seconds on the half hour for Ca.
I have a set local available for $25each
https://www.bulkreefsupply.com/brs-2-part-doser-1-1-ml-per-minute.html