"Steve" wrote in message
.128...
wrote on 21 Dec 2007 in group alt.home.repair:

I had a Kohler Devonshire whirlpool tub installed. When used with
jets turned on a yellow brown smudge is left on the tub at the water
level. I had a filter put on my hot water heater (between the heater
and the tub) thinking that there must be impurities coming from the
water heater. Now I know there are none from the hot water heater -
the problem continues. I had a service tech from Kohler check this
out but he could not find the cause of the problem.

I've had that with every jetted tub I've ever used, including a hot tub. I
suspect the bubbles bring body oil and dirt to the surface where it
deposits on the walls.

Could be... What happens when the OP runs the tub WITHOUT anyone actually
getting into it?