Foam used to drive me crazy too, it looks harmless, but it’s usually a sign there’s buildup in the water. Most of the time it comes from things like leftover soap in swimsuits, body oils, or hair products that get whipped up when the jets turn on.
What really helped me was doing a deep clean cycle before draining, I ran a spa line cleaner through the system, then refilled with fresh water. After that, I made sure everyone rinses off first and only wears swimsuits that were washed without detergent. I also add a quick filter rinse every week now.
Since doing that, I rarely get foam anymore, and if a little shows up, one quick scoop of defoamer clears it instantly. It’s all about keeping the water fresh and free from residue.