you can use a piece of women's nylon over the filter grate, or they make sponge tip for filter intakes
the only negative of the sponge tips, is they clog up, & require cleaning much more often than the filter does, but they are reusable just like the sponges on a sponge filter or other hang on tank filter... just squeeze them out in tank water... you often find adults & babies alike feeding on the sponges or mesh over the filter intake
I know you're in the UK, but this is similar to what I'm talking about... I sure similar are available there...
the only negative of the sponge tips, is they clog up, & require cleaning much more often than the filter does, but they are reusable just like the sponges on a sponge filter or other hang on tank filter... just squeeze them out in tank water... you often find adults & babies alike feeding on the sponges or mesh over the filter intake
I know you're in the UK, but this is similar to what I'm talking about... I sure similar are available there...