Be patient, it is a big catalog.
Look at page 10. See the 'concept' drawing. The box with a cut away view into the interior. The pump is not just in a box, but there are also baffles that keep the roots out, and trap debris.
This product is intended to be placed outside the pond, next to the pond, using flexible pond liner. Something like it, but smaller, works better inside a hard surfaced pond (stock tank or other). The idea is not just a mesh box with a sponge, but a better intake system.
Then scroll to page 11. See the tower-like thing on the far right? It has a grid-like thing attached at the bottom. The pump fits in the tower. The lid can be submerged or not, whatever fits. The grid-thing extends along the bottom of the pond. This is where the roots would get in, I am afraid, but at least there is plenty of room for them to grow before they are a problem. Can go longer between having to clean out the roots.
Or, go with the style you pictured, but yes, monthly or even weekly cleaning when the plants and fish are highly active. Mine needed weekly cleaning and I could not keep up. Burned out the pump. If you start with something like this, perhaps add another box with coarser media around this box.
Here is one possible box. I have also used the crates that grocery stores get milk and similar products in, and a Matala sort of mesh as primary filter.