That's way too much epsom salt. I NEVER add it to my ferts or res, only foliar feed, at 1/4 teaspoon per gallon.
Drinking water? Like, bottled water? Do yo uknow the sodium content?
You say flowering nutes, but what kind? Tehy are all different and have different application rates.
Your plants are not deficient, they are severely locked out. Change your res right away to get any residual magnesium out of the RW and bucket. Go to tap water instead if you re using bottled drinking water, but check the tap water first for pH and EC. If you have 'soft' water, you'll need calmag. Look around here for info on that. Feed your bloom fert exactly as the manufacturer says, at pH 6.0, and keep it stable.