question about small fish and pump Koi

I recently added an external bio filter to my pond as an extra filter mechanism. It is set up with a pump in the pond, with a line to the filter and then a line back to the pond. I have small koi, medium goldfish and mosquito fish. I was worried about the mosquito fish getting sucked into the pump so I covered the pump with some netting but the netting gets clogged with algae pretty quickly. The mosquito fish are breeding like crazy so Im not too worried about losing a few of those.

I recently added an external bio filter to my pond as an extra filter mechanism. It is set up with a pump in the pond, with a line to the filter and then a line back to the pond. Its really easy to back flush and has been a great addition but I am having a problem. I have small koi, medium goldfish and mosquito fish. I was worried about the mosquito fish getting sucked into the pump so I covered the pump with some netting but the netting gets clogged with algae pretty quickly. Do most people run the pumps without any sort of protection? The mosquito fish are breeding like crazy so Im not too worried about losing a few of those. Thanks!