I don’t think that a perfectly clean spa should need foam free but occasionally I due. Not sure why exactly when things test good and looks crystal clear until the blowers come on. Just a good quick squirt of foam free and you can hear and watch the foam disappear usually within a few seconds.
Works as intended if you’ve got foam

Really great!

it's awesome!!

Hot tub owner for 6 years. I have used a lot of different products. This is by far the best, longest lasting and economical defoamer I have tried. I'll never go back to another product. I just bought a 6 pack. Buy 5 get 1 free. Great deal!

Knocks foam down. Ultimately an early charge of water required. Temporary fix only.