After adding 100 ml of detergent to about 125 liters of water (top nozzle) was immediately after being switched white foam. That the foam was white and not brown, I am now times out back that my hot tub is clean and not to a lack of effect of the cleaner.
In addition, I can not understand what some write here for a nonsense. It does not smell strongly and the acrylic tub was then not defective. Fully satisfied = full star number.