I use the trays. Also - I apply MultiPure Water (WWW.MultiPureUSA.com/dhinton) a water purification system that is proven effective by the states of Wisconsin, California and Colorado as well as the NSF and UL.(All independent 3rd party evaluations.) Also, then I put azomite on the top of the canadian peat moss. Where do you get the sea water for your wheatgrass?