That and the fact you had a doser and everything was probably pretty stable and now it's probably all outa wack

What do u guys do to lower phosphate I u don't wanna run a reactor? Is me running the phosphate remover bag passive in sump good enough? I'm trying to remove as much green hair by manually pulling it out on each water change as much as possible. I put 4 teaspoon of seachem magnesium mix with ro 2x a week manually in my 75g but that doesn't seem to be able to get it to 1400 lvl. I'm scared of putting too much too fast n shocking my system. Did it set it up to my doser yet because it's not at the lvl I want it to be.

You will never raise your mag with that method get bulk mag chloride and bulk mag sulphate from jl follow this recipe. http://www.reefkeeping.com/issues/2006-02/rhf/
Pretty sure it's safe to raise mag by 100 ppm a day. This is a link for a reef calculator to figure out the amount to use.
http://reef.diesyst.com/chemcalc/chemcalc.html

As for phosphate highly doubt your method at use now will do anything you should be running a reactor with rowa or gfo even with a reactor it's gonna take a bit to remove phosphates now.