Might not be the button, they use air pressure to travel through a tube to a remote switch near the motor. You have to get under it to see if the tubing is loose or cracked.
Hi Virginia,
I've done some research on tubs with jets, and from what I've read I wouldn't put anything granular in the water.
The granules may damage your pump and also when the water stops some granules will be left in the pipes, where they will decompose and turn into.... well, I don't think it'll be nice.
try a plumbers shop as it is a whirlpool tub
you state that it is a whirlpool tub then you say don't know what brand of tub it is
whirlpool is a brand name
any way the plumbers display of bathroom units and tubs will help you as the jets used are generic and not specific for the tub