Spa Choice Foam Free shrinks foam on contact. Foam is a common problem in spas and hot tubs that is caused by many sources including: hair products, deodorants, lotions, laundry soap residue, spilt drinks and cheap or excessive chemical use. Foam Free is specifically designed for hot water application. Shake well before using. Apply 3 ounces of this product to the foamy area. Use as often as needed to prevent foam build-up.