Tad,

"Never" means under normal circumstances, maintained by an "educated consumer". Your predecessor was anything but.

You can rest assured that getting "Pool Stored" meant he dumped in a lot of junk without any idea of what it did or what it was good for. Clearly, one of those many additives gummed up the sand, a clear recipe for replacement. (Ask anyone having completed a Baq conversion).

These days 200# of sand is about $24.-- a cheap enough fix to try even if that was not your problem.

Let's understand the "mantra" of "never" changing your sand: It means that unless your sand is actually fouled, as yours was, replacement is not a necessary part of sand filter maintenance, so don't waste money on new sand every year or even every 5 years.

That's all it means: No more, no less. If it ain't broke, don't fix it. But if it is broke (as yours was) then, by all means, fix it.