Protein skimmer stand.

This is a reinforcing metal stand that goes under steel mesh that goes into concrete slabs under houses, driveways and commercial buildings,etc.

They are designed to keep the steel near the mid section of the concrete as it goes off so the steel is not close to the external moisture that would send it rusty and the steel rusting can make the concrete explode in tiny sections and weaken the integrity of the slab.

This one can be cut to the desired height for your skimmer or anything else needing a stand in the sump.

They can be bought from places like bunnings,etc.