It's best to avoid introducing detergents to your spa water, as this will encourage foam to form. If you are experiencing excessive foaming, you can reduce and inhibit foam build up in your hot tub with this Spa Foam Reducer.
You can avoid foam buildup by following the golden rules:
Following these two golden rules will prevent detergents from getting into the water.
Adding a few drops of Spa Foam Reducer directly to the water will cause foam to dissipate almost immediately.
COSHH / MSDS Safety Sheet