I normally dose 1&1/2 cups of each per day 150 gals. Mostly softies and some SPS no other supplements.
I just went on vacation for eight days had two gallons of each hooked up to a two channel dosing pump. Alk was 5 DKH and Ca was 400, both jugs were empty. Everything survived, some Zoas weren't happy with the low ALK. I've tried Kalkwasser, but mixing per the instructions really didn't seem to aid enough to justify the added work.
Tony