8 Inch Filter Brushes in Rectangular Chambers – Double Interlocked Spacing
How Many 8 Inch Brushes Do I Need for a Rectangular Chamber?
8 inch (20cm) diameter Black Knight filter brushes are our largest size and are particularly well suited to large rectangular filter chambers. Their greater diameter means fewer brushes are needed to fill a given space, making them a practical choice for high-volume commercial or large domestic pond installations.
What is Double Interlocked Spacing?
Double interlocked spacing means each row of brushes is offset from the rows either side, so the brushes nestle into the gaps between one another rather than sitting in straight lines. This arrangement eliminates wasted space, prevents water from bypassing the filter medium and maximises the surface area available for biological filtration.
Worked Example
A rectangular chamber measuring 35 x 28 inches (87.5 x 70cm) would require 20 brushes of 8 inch (20cm) diameter using double interlocked spacing to fill it effectively. The diagram illustrates this arrangement.
To calculate how many brushes you need for your own chamber, measure the internal dimensions and use this example as your guide. Our team is happy to help with any calculations — just get in touch with your chamber measurements.
Are 8 Inch Brushes Right for My Setup?
8 inch brushes are best suited to large rectangular chambers. If your chamber is circular, we recommend using smaller brushes instead — 8 inch brushes do not pack efficiently into circular spaces and can leave large gaps that reduce filtration performance. For smaller rectangular chambers, 4 inch brushes or 6 inch brushes will generally be a more practical option.
Note: 8 inch brushes can be pushed together a little more tightly if required.