Need ideas to block skimmer intake from fish

I have an octopus BH-100F HOB skimmer.

I am using the surface skimmer attachment. It is sticking up out of the water a little bit. Maybe an inch.

My blenny likes to get in there and from there into the skimmer. It's a real pain to get him out.



I'm looking for SAFE things I can use to close up the top of this surface skimmer to keep the blenny and any other critters out.

One idea i had was one of those steel bristle pads - but I'm thinking that might have trace elements leaching I don't want. I want to stick it in the top around the tube so water won't really be going through it... but I'd rather not have a nitrate factory there either.

Don't want a sock on the tube because I don't want to stick my hands in the water to take it out to clean it.


Any ideas???

 

Gutter guard. You can get it at home depot for pretty cheap.