Skim Kleen Belt Sizing Tool How Do I Know My Belt Length? Step 1: Find ‘A’ Measure from the bottom of your Skim Kleen housing to the water surface level. If you have an -ES Extension Stand, measure from the top of the extension stand to the water level Step 2: 2A +7′ = Belt Length Double your measured value, then add 7 feet This is your ideal belt length!