Hello. Yes flush with tap water. I extra flush. I use 1 ounce of 35% hydrogen peroxide to 5 gallons of water. Do a test. Cut some buds (enough for a couple of joints) before you flush and dry them. Put away in a air tight container. when your grow is done and cured pull out the unflushed buds and do a side by side taste test. You decide for your next grow.