Why was it compacted? Dunno, maybe that's just what it does eventually? Probably was never properly backwashed in its early years.

I went ahead and turned it to filter, no grey cloud into the pool, so that's good.

Before I replaced the spider gasket the system ran at about 12psi, because it was leaking water around the gasket. With the new gasket but before cleaning the sand, it jumped up to 18psi. Now with the sand cleaned it's running at 15psi.

TW