..Agree ,I have experimented with different ways of dosing limewater but never with adding it in straight powder form directly to the tank.I think most of it would likely precipitate Ca & alk ,maybe Mg as well,and cause problems with stability.It really should be dripped ;the slower the better,ime.
Theres several ways people go about dosing.I like the still reservoir equipted with a float switch and diaphram pump ,but thats just me.
One simple way that I know another reefer has been using for a few years now. Just an idea ,maybe a plastic garbage can with a float valve plumbed to your sump might be worth considering.Very economical,simple and effective way to dose ,keeping ca & alk on par while replacing evaporation at the same time.
A little math initially so you could figure your tanks consuption rate is pretty much all it would take.
Just an idea good luck to you with whatever you decide.
-Steve