Why 8 Inch Filter Brushes Don’t Suit Circular Chambers
8 inch (20cm) diameter Black Knight filter brushes are our largest size and are highly effective in rectangular filter chambers. However, they are not recommended for use in circular chambers.
So why are 8 Inch Brushes not Suitable for Circular Chambers?
The larger diameter of 8 inch brushes means they leave significant gaps when placed inside a circular chamber. These gaps allow water to pass through the filter without making proper contact with the brush medium, which reduces filtration efficiency both mechanically and biologically. The larger the brush relative to the chamber, the more pronounced this problem becomes.
What Should I Use Instead?
For circular chambers, we recommend using smaller diameter brushes that pack together far more efficiently, minimising gaps and ensuring the maximum amount of water passes through the filter medium:
- 4 inch brushes in circular chambers — ideal for smaller to medium circular chambers, packing together with very little wasted space
- 6 inch brushes in circular chambers — suit larger circular chambers and require fewer units to achieve good coverage
If you have a rectangular chamber and want to use 8 inch brushes, see our 8 inch rectangular chamber spacing guide.