dwc watering question

im using 5 gallon buckets with 3 gallons of water in each one. the roots have gotten to the point to where they are at the bottom of the bucket..
my question is can i use less water now that the roots are longer...
im also on a budget for my nutes so please let me know if i can go down to 1 or 2 gallons now that the roots are longer/stronger!!?

you might be able to go down a gallon. depending on how big your plants are they might drink more water.

i gotcha would it be a good idea or no to put a gallon of nute water and a gallon of reg r/o water?