I get that every spring when I first start up my waterfall and filter, some
years worse than others, and have read here it is protein - not sure about
that, but it is gone fairly quickly
Gale :~)

600 gal pond, London UK. Hozelock pump and pressurised filter, plus
fountain. The fountain and filter return are creating a foam which clings
to plants and feeding ring. I assume it does no harm, but is there any way
I can illiminate this?