my plant drinks half my rez each day and I run 1600ppm nutes
You need a bigger rez
It's totally understandable people want big buds, big fruits, but that's not something just mj growers want, it's a much larger priority in the food industry. With the ever increasing population it is no less than a matter of life and death.
Huge commercial greenhouses don't want to use any more nutes than needed. Besides the cost of the nutes, limits on the max amount of pollution force them to get the max yields with as little amount of nutrient use and waste as possible.
Point is, it's been tested,over and over, and still is today. For anyone interested in the balance between water/nutrients/yield I higly recommend reading some books on nutrient usage in commercial greenhouses. Sure cannabis is a unique plant, it's still plant and most things apply.
Besides the decreased water uptake, another test outcome I remember well is that even though you can push a plant to take up more nutrients, it doesn't necessarily mean it will produce more yield, it'll build up a larger reserve (which in optimal indoor conditions is overkill).
All in all it's best to look at the plants first then the meters. Just because the ppm dropped doesn't mean it actually 'needs' a higher ppm.