The plan was to have caves behind th eopenings on the right and mesh over the ones on the left.
Here are the "caves" with a coat of drylok
Siliconed in place , I forgot to take a picture but the inside of the cave is painted to match the front of the background.Here you can alos see the fittings for the outflows. Water will flow from the caves into the tank and return to the pump via the openings covered in mesh.
Mesh over the openings
I'll get some pics from the front once this has all cured.