Hi PoolDoc,
High school, it used to be in my realm to do that when I was in grad school, but those days are long gone for me too. AP Physics no prob, but DiffyQ would take a hefty amount of re-studying on my part.

Thanks Aylad about the sand filter advice, it actually runs just fine, I only became concerned when other people told me that I "needed" to replace the sand. Thanks again! I'm going to print this entire thread!