I wrap up my nutrient cycle with just a teaspoon of molasses with 2 1/2 gallons of water around the 5th or 6th week of flowering to give the bud a nice sweet flavor, and then I just go with straight water the last two weeks. That'll flush any residual nutes out, so you don't end up smoking them. Some go 7 days, but I prefer the full two weeks just to make sure.