Having the ability to adjust the height that your skimmer sits in the water can change how the skimmer pulls air and water into its reaction chamber. Most skimmers will have a sweet spot, that on your particular tank will run best. By having an adjustable skimmer stand you can fine tune the height of your skimmer to get the best results possible on your particular system.
Most skimmers can run at different depths and from system to system either raising or lowing your skimmer in your sump could easily result in better performance and skimate production. Depending on the depth of a skimmer the characteristics of how air is pulled into the skimmer pumps venturi changes dramatically.
Please note: These skimmers all have an adjustable height from 10cm to 15cm