How do you keep a garden pond scum free?

Since we want fish at some point chlorine is out, it does have a pump in it for a mini waterfall effect but that doesn’t seem to have stopped bacteria from spawning as now when the pump’s on a layer of foam forms on the surface.

Anyone know how to get rid of it and stop it happening again without poisoning the water for future fish?

Barley straw. Works like a charm, and no harm to fish.

Always keep some bail money handy for the garden pond scum.

(Other than that, I have heard good things about the barley straw mats, but I have no experience with them.)

Read about foam in a pond here and here. Buy stuff to pour into the pond to get rid of foam here and here.