What the fuck are you stuck on stupid?
Why would you wanna?
Chillax, be nice Ghetto. Mold and the fact that plants drink and uptake more in strong light would be my guess. If relative humidity is low i dont see why not but still it is not recomended for indoor grows, will also raise RH but with good circulation and extraction then fine, ok do it but be ye warned.
Water is a good source of cal/mag usually, spray it on the plants, i see no problems with foliar feeding epsom salts but epsom salts will not cure a calcium deficiency and RO water has a habit of sucking up the cal/mag so could be why your mag deficient in the first place, bad water with little cal/mag. Good luck dude. Peace