Phosphates are the most likely cause.

Yes — the foam is a symptom, not the problem itself. In a pool-spa combo, the jets aerate the water, and if your chemistry is off, you get a bubble bath.

Most foam comes from phosphates. They get in from body oils, lotions, sunscreen, and even some pool chemicals. Phosphates act like soap — they stabilize bubbles. Fix the phosphates, and the foam disappears on its own.

A phosphate remover (like Orenda or SeaKlear) usually clears it in one treatment. While you’re at it, check your calcium hardness and total dissolved solids. Low calcium and high TDS both make foam worse.

Don’t just add a defoamer. That masks the problem for a day. You want the chemistry right so the foam doesn’t come back.

Future You will thank you when the spa doesn