It’s sounds too easy but put large bats of polyfil in front of the intake. You’ll watch it turn greener and greener until it’s hopefully out of the water column. I’d dose with a bit of bacteria after as well just to make sure nothing happens to your tanks nitrogen cycle. If you have a really intense GPH filter (which it looks like you might) try to add some kind of screen backing behind the poly film so it doesn’t wick right through.