Cleaning whirlpool tub/jacuzzi?

The previous owners never used it as a jacuzzi - only to give the baby a bath. I scrubbed it and cleaned the jets when we moved in and run the hot water in it weekly even though we don't use it. The other night we decided we wanted to try to use it, and it was a comedy of errors. The water filled up nice and clear until it was almost full, then started turning brown. This happens every time I try to put it on. The hot water starts out clear and clear in the tub and about 1/2 way full the water in the tub starts turning brown and yucky. When I drain the water, there's brownish/ black sediment on the bottom of the tub.

I thought it was the hot water heater for sure (it's 9 years old), but my plumber was just here and says he doesn't think that's it since I am not seeing brown water come from the spout. He thinks it's most likely that when the water level reaches the jets, there is some sort of dirt in the jets that is turning the water brown. He said if I use HE laundry detergent or dishwashing liquid, and run it a few times, it should be good to go.

Anyone have experience with this or a suggestion?

Thanks!

Re: Cleaning whirlpool tub/jacuzzi?

I've tried the whole dishwashing liquid idea and a few other things and none of them worked as well as I thought they should. I found something at Bed Bath & Beyond called "Spa Genie-Jetted Bath Flush Cleaner." I think it was $20, its in a white bottle with a red cap.