Buy bloom sea mineral, very concentrated. Just use 1 ml/gal as a mag. Supplement when in veg. When in flower up to 2ml/gl. When using overdrive or powder koolbloom in week 6th or 7th up the doses to 3ml/gal or more, but no more than 5ml. As u hitting your girls with p they also need mag. Good luck.
Make sure u flush with flushing agent. Flushing agent will break down the salt build up. Like taking a shower with and without soap. I like to use gh florakleen. Good luck.