Questoin for Stinky or anyone that can answer...

At the pharmacy here they sell "treated Demineralized water" that is equivalent to distilled water it sais on the bottle.
It also states this:
"Atlas brand treated Demineralized water contains less than 10 parts per million of solids (<10ppm). The treatment process has made this water pure and practically free from chlorides, sulfates, carbonates and calcium and is equivalent to distilled water." It then goes on by saying it "prolongs the life of electric kettles, steam irons, humidifiers, radiators etc... because there are no deposits from the water (crusty film) and it is perfect for misting plants."
Ha! sounds good!

So what do you all think of this water? any good to you?
Would like to know your thoughts, maybe I should add calcium to this water?
Note that my plant is going into FLOWER stage this weekend.
Thank you!