Hey LouSchott, you always want a flush just to avoid that harshness on the inhale, no matter what system you're using. Nutes stick to that film more than in ebb and flow hydro systems that dont use NFT , but they get flushed out pretty quick. When you get your trychomes perfectly how you want them , then just go straight plain water for two days or 60hrs and you'll be golden, hope this helps ! 🚀