Version 10 includes the following modifications:
The filter size (height and width) are the same as the current design, but the height of the spout and the diffuser location has changed. The spout is higher, and therefore the nose of the filter is shaped differently.
- The filtration sand (the fine sand bed) depth is increased by 10 cm (4 inches) to 55 cm (21.6 inches) in Version 10. This means that there is about 22% more fine sand in the filter.
- The separating gravel (6 mm or ¼ inch) and underdrain gravel (12 mm or ½ inch) layers remain the same.
- The depth of the reservoir (which provides the gravity ‘head' pressure) is reduced by 10 cm (4 inches) to 17 cm (6.7 inches). This will cause the initial flow rate (when the filter has been filled to the top) to be about 1/3 less.
- The recommended flow rate is 0.4 L/min (measured when the reservoir is full to the top). It will take a longer period of time to filter the same volume of water.
- The maximum fill volume is 12 litres in Version 10 compared with about 18 litres in the previous design. This means that the filter will need to be filled more often to treat the same amount of water.
Table: Comparing Version 8/9 and Version 10
| Version 8/9 | Version 10 | |
| Depth of resevoir | 27cm (10.6 inches) | 17cm (6.7 inches) |
| Maximum fill volume | 18 litres | 12 litres |
| Filtration sand depth (fine sand bed) |
45cm (17.7 inches) | 55cm (21.6 inches) |
| Separating gravel (6mm or 1/4 inch) |
5cm (2 inches) | 5cm (2 inches) |
| Underdrain gravel (12mm or 1/2 inch) |
5cm (2 inches) | 5cm (2 inches) |
| Flow rate | 0.6 L /min | 0.4 L /min |
For more information on the changes made for Version 10, see this presentation.
