DE Pressure high after inadvertent use of PACL 108

Pool store inadvertently gave me container of Poly aluminum cloride (PACL 108) instead of chlorine (same container) I put ~1 gallon into 15,000 Gallon pool before I realized the mistake...next day bottom of pool gray skim on bottom... vacuumed...pool is clear, water tests fine... but de pressure runs high after 40-50min (starts at 14, rises to 25)...cleaned de grids and have vacuumed to waste several times,,,but still have same short cycle issue...any ideas? prior to this filter would run for 10hrs at a clip with no issue...

Sorry, no idea. You seem to have done most of the things I'd have thought of.

I should note, that if you have LIVE algae still in the pool, that will produce EXACTLY the pattern you describe.

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