[pogodzib]

Cast is better, but more costly. For anything that holds water with the water being on one side but not the other (skimmers, sumps, etc...) I prefer to stick with cast. Since baffles have water on both sides and if they were to fail, it wouldn't flood the floor, extruded is fine. The problem with extruded is that they can swell, hence causing it to leak at joints if different pieces swell at different rates. With that said, there are some cheaper brands of skimmers that use extruded acrylic without issues.

BTW - Welcome to RB!!!