I hope this is the proper place to raise this question. I have a client that basically is raising grass hydroponically in 4 inches of clay loam chemical soup. He does indeed have a thatch problem and will be renting an aerator this fall, but will never allow grass clippings to be left behind. I understand that 'thatch' is a loaded term and the university extension offices across the nation say different things. One says thatch is a dark brown 'felt like' layer of dead roots and stems, and grass clippings will help digest that layer, as they themselves, quickly break down. Another says that 'thatch' is the spongy layer of dead plants and grass clippings and that you need to be able to see soil within a half an inch of this 'thatch'. Maintenance routines will be vary greatly, even oppose one another depending of which philosophy one believes in. What has your years of observation and experience shown you in this area?