Almost out of
nutrients? Something doesn’t seem right. I start growing in May and go all the way into late October and never used a gallon of nutrients that whole time using a reservoir that holds 45 gallons of water. You must be over feeding those plants you don’t need to do that cut down the amount of nutrients you use. You can also sometimes go more that a week depending what stage of growing you are in.
Great job on the 55 gallon reservoir!