Is my sand filter working?

[Watermom]

No.

[PoolDoc]

The problem with food grade DE is that it's an unknown quantity for us, with respect to filtration. If your DE is LESS coarse then filter DE, it may go through even a properly functioning filter. If it's MORE coarse than filter DE, it may be caught by even a non-working filter. It *might* be the same as filter DE -- food grade baking soda is chemically identical to pool "alkalinity increaser" -- but we don't know that.