My says 2ml to 5ml so if you want to go light, I'd say 2ml per gallon would be good. I hear it's hard to burn the plants with too much calmag but I have no exp with higher doses.
I accidently killed a beauty,in a rush mixed 10ml per gal.Five gal bucket into Her dead within an hour.Even killed the frogs living in her mix.That was my last attempt at an outdoor scrog,maybe one this year but I never use more than 2ml and I triple check that shit.