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In a tub with bypass filtration, the suction fittings are frequently plumbed in a Tee fitting with the filters. As such, as the filter gets dirty - or worse, gets plugged - more and more suction is applied to the suction fittings.So if you have one of these tubs, don't panic. They are still FAR safer than some old commercial in-ground tub you may find at the health club, resort or other publice place. But you should still keep those filters clean.