Not at all. Generally, many people here will tell you (me included) that filter sand only needs to be changed if it gets gummed up or has a HORRID algae infestation, or something else that prevents it functioning, or you had pull it out anyway because of a broken lateral.

It doesn't really HURT to change sand, but, again, most sand users find it filters better as it gets older, so why change it? Some folks here have the same sand for a dozen years--I'm going on Year 5 myself.

You MUST use filter sand in your filter. Period. You should be able to find it for $5-$6/50lb bag....that's about $70/filter.

But is there a compelling reason to change the sand or are you just changing it to change it?