The local resourcerie has a couple of pump/filters in - the ones for the inflatable “swimming” pools.
Would it work to filter some of the algae from the pond - or just bung everything up.
They’re very cheap - pretty much the same price as the liquids you add to make it clump.
Suspect I’ll need to bodge a mesh
No is the short answer, same reason they cant filter algae from pools, we have to kill it first then filter the dead algae. You can use barley straw in a pond as that produces hydrogen peroxide once it rots down. A well oxiginated pond will aid the breakdown of the barley straw.
I tried that as an experiment with one of my ponds, years ago, didn’t seem to make any difference.
Barley straw takes quite some time to get going, but it does eventually work
Hence the oxygenation helps the process.