Is your filter not working well? Remember the old saying: If it ain't broke.....

As filter sand gets older two things happen: It wears down and it collects dirt that doesn't wash off. Both are good things because it makes the sand filter better, making it catch smaller and smaller particles. I am still using the sand that was installed in the filter for this, the 12th season and I have NO reason to change it.

Try a little DE in it first, 1/4 to 1/3 cup at a time, just enough to raise the pressure 1 or 2 lbs. DE will significantly improve the filtering of a sand filter. The water goes from clear to glistening! DE is cheap, too...I've been using the same 10lb box for 4 or 5 years now and paid less than $10 for it. Save you work, save you effort, for maybe a buck or two outlay a season.