Many filters have a combination drain which can open about 3/4 inch for draining water or about 1.5" for washing out the sand. If your's doen't have that large outer opening, then a shop vac, as Jason said, is about your only option.
Newtopools said:All I can tell you is that it's a Purex Triton filter and it was purchased in 1995 (not by me). The manual for it is utterly useless as it offers no information regarding changing the sand. At this point I'm starting to think it's best to just buy a new filter in the spring.
Thoughts?