i thought the max amt. on the bottle was 5ml...my bottle says 2-5ml per gallon...i go half strength but believe i need to up my dose closer to 4 or 5 instead of the 2.5 ml per gal i regularly use (only during flowering)...most base nutrients solutions (Pro-Gro, Bio-Grow) have small amounts of cal-mag that i was taught was more than enough during veg. growth...but what the hell do i know? :thumbsup: