thanks for the reply.. I actually DID find the two page manual but it doesn't say much about maintenance. I gather the permanent media means I don't need to change sand (didn't know something like that existed). The filter is 40 years old.

pics:

[IMG]http://i58.tinypic.com/*****.jpg[/IMG]

[IMG]http://i60.tinypic.com/*****.jpg[/IMG]