I have a dwc system with a. Spray system also, and my plant will drink a gallon and a half in one day, sometimes more, sometimes less, but she is a very thristy girl! She is also in flower, vegg, she was fine, could go 4-5 days without topping off, once she hit 12/12 she gulps it down. Plants drink a lot in DWC, they sit in the soultion the whole time, so they fed whenever they want. Just make sure u have a large enough reservoir.