This construction is particularly suitable when extreme levels of contamination are expected. The skimmers should then be accommodated in a separate cover pit so that the contamination is transported directly in front of the skimmer when rolling up. All the contamination that does not float drops to the bottom of the cover pit, which can be emptied and cleaned from time to time.
| Construction: | The roller system is positioned in a separate pit behind the pool. The pit is filled with water and connected to the pool through a gap. |
| Installation: | Only for new pools |
| Maximum size: | 25 m x 50 m (larger sizes depending on pool shape) |
| Drive unit in separate motor pit: | Drive unit mounted on the shaft, or chain drive |
| Drive unit without motor pit: | Tubular motor (not always possible, dependent on pool width and depth) |
| Cover slats: | Standard slats 60 mm wide and 14 mm thick |
| Guidelines: | Installation approved only for private pools |