GENUINE BLACK KNIGHT 20" x 6" FILTER BRUSHES x 25

What are Black Knight filter brushes?
Black Knight filter brushes are made from the very highest quality Hydrotek polypropylene twisted into two stainless steel wires to form a cylindrical brush with a loop at one end for hanging. The other end is capped with a plastic knob for safety.    
They last indefinitely and are the easiest to use, most efficient and most cost-effective pond filter medium you can buy.    Our brushes are used in filtration systems in fish farms, hatcheries, public aquaria, domestic fish ponds and research institutes in this country and abroad. No other filter medium is as widely used or has been as extensively tested and proved.  

What are the benefits of Black Knight filter brushes?

They:
are very easy to use    
do not need replacing
are lightweight
don't clog up as many other materials do
are non-toxic
are very easy to clean
never wear out
are by far the best medium for removing suspended particles of waste
cost less than any other material that does an equivalent job
are tried and tested all over the world
provide a massive surface area for biological colonisation
do not require expensive support frames