I know this is a really old thread and I can't believe nobody has replied but, I'll reply in order to share my experience with the so called "Deck Clean Deckwash System" among other shortcomings of our new Cub Cadet GTX2100.
A couple of months ago we were in the market for a very good lawn and garden tractor so my wife could mow our 3 to 4 acres of grass. We did not trifle and bought the top model our Cub Cadet dealer had in stock, the GTX2100 with 54" manufactured deck, power steering and electric deck lift. In short, we are VERY disappointed in this tractor overall.
Specifically, staying relevant to this thread, the deck wash system is pretty useless. It does do some cleaning but we find we have to spend 5 to 10 minutes sitting there with the water connected, running the tractor wide open, deck engaged, to make any sort of difference at all, and even then, the deck is far from clean. No amount of deck washing will get, and keep, this deck clean. We have cut our grass about four times now and we've had the deck off the tractor three times for cleaning. The deck is impossible to keep clean. I've been cutting large areas of grass for 30 years with a variety of mowers and I've never seen a mower plug up as fast or as completely as this deck plugs up. After cutting about three acres, the deck is so plugged that the 23 HP engine boggs down in just a medium heavy cut...very poor performance for such a tractor.
I see no remedy for this obvious design flaw. I believe this issue may be caused by the depth of this manufactured deck. The deck seems to be so deep, especially at the left end, that there is not enough air movement to push the grass clippings out.
In summary, No, I am not a believer in Deck Wash and I am not a believer in Cub Cadet. I'll be selling this unit asap in favour of something else, that hopefully performs better. (this isn't the only problem we've had with this very expensive tractor)