There are many things that cause foaming in a spa: There are products that we bring into the water; body lotions, deodorant, hair products, and even laundry soap residue on bathing suits. Other causes to foaming are soft water, a high pH level, and high levels of Total Dissolved Solids which usually results in waiting too long to change your water.
HT Foam Away instantly eliminates these types of foaming issues. But the correction is only temporary and will resurface shortly thereafter until the root problem is corrected.
Remember foaming will not harm you or your hot tub but often the cause of foaming may affect the sanitizer level, so test it after any high-level occurrence of foaming.