Ammonia is released into a chlorine filled pool if you use an SWG? Excuse me, but doesn't mixing ammonia and chlorine result in a deadly gas being produced, which is why you are warned to NEVER mix the two for home cleaning?

If you put DE in your sand filter, you'll probably have to add more every time you backwash. Since you only add a half/cup to a cup, a 10-15 lb box should EASILY last the season. I use this method as well and like it.