I have a aquamedic 4 pump doser. It does the job but its not perfect.
I run my calcium at 3 mins every 3hours(-+4.5ml every 3 hours) and alk at 3.5 minutes every 3 hours, I try to keep them hour and a half alternating. I have my alk tube going into the filter sock and caciuml tube zap-straped to the overflow output, and mag directly into the sump. Oviosuly the dosing amount will vary according to you tanks consumption.