How to Clean Bathtub Jets Without Buying Special Products
The first time I ran my jetted tub, a gray film floated out of the jets and I climbed out faster than I got in. The previous owners had clearly never cleaned the things. I assumed I needed a special cleaner that costs twenty bucks a bottle.
Nope. The stuff under my sink did the job.
Why jets get dirty in the first place
Jetted tubs hold water inside the pipes even after you drain the tub. Soap scum, skin cells, and bacteria collect in that trapped water. If you do not clean the system, the next bath blows all of it back at you. That gray film was months of buildup.
The vinegar soak method
The standard clean is a hot water and vinegar soak. Fill the tub with hot water, about 2 inches above the highest jet. Add 2 cups of white vinegar. Run the jets for 15 minutes, drain, then fill with cold water and run the jets for 5 more minutes to rinse.

Do this once a month if you use the tub regularly, or before your first soak if you just moved in. The vinegar dissolves soap scum and kills most of the bacteria without harsh chemicals.
Dishwasher detergent for the stubborn stuff
If the vinegar soak does not cut it, add a squirt of dishwasher detergent or a sprinkle of dishwasher powder to the water before running the jets. The enzymes break down the gunk that vinegar misses. This is the closest thing to the fancy jet cleaners, and it costs pennies.
Rinse thoroughly after. You do not want dishwasher soap residue in your bath.
Clean the jets themselves
The little nozzles can be scrubbed with an old toothbrush dipped in vinegar. Pull off any removable jet covers if you can. Soak them in a bowl of vinegar for 15 minutes, scrub, and pop them back on.
How often you actually need to do this
Weekly if you are a heavy user, monthly if you use the tub a few times a month. If you only use it occasionally, do a quick 5 minute vinegar run the day before you want to soak. That clears out anything that has been sitting in the pipes.
The habit that prevents buildup
After every single bath, run the jets with plain cold water for 2 to 3 minutes before draining. This pushes most of the soapy water out of the pipes and cuts down the gunk dramatically. It adds three minutes to your routine and saves you from monthly scrubbing.
Quick Summary: Fill the tub above the jets with hot water and 2 cups of vinegar, run the jets 15 minutes, then rinse. Add dishwasher detergent for heavy buildup.
I ran the vinegar soak the day I moved in, and the second bath came out crystal clear. The fancy cleaner stayed on the shelf, and it still is there.