You're allowed to clean your Biofalls once per year during your spring clean-out. After that, don't touch them.
That might sound terrible if you're a neat freak, but trust us: your pond will thank you for refraining.
Your biofilter is one of the primary places in your pond that beneficial bacteria call home. All the nooks and crannies on your filter mat, Bioballs or lava rock gives these bacteria a place to grow as they do the important jobs of eating ammonia and nitrites. This process keeps your fish healthy and your water clear. (Learn more about your pond ecosystem here.)
When you clean your Biofalls, you wipe out this delicate ecosystem that your pond has spent so much time building up. We recommend cleaning it only once per year, usually as part of an annual spring clean-out, before the water temperature in the pond is consistently above 55 degrees. If you perform a clean-out when the water is warmer, after bacteria colonies form, the balance of the ecosystem will again be thrown off, and your pond will go through another “green phase” before the bacteria colonies re-establish themselves again. (Click here to learn more about spring pond clean-outs.)
The best way to clean your biofilter is to gently rinse the filter mat and Bioballs in pond water. Rinsing them this way will remove any gunk and large debris without killing too much of the ecosystem your pond spent all year creating.
There is one exception to the once-per-year cleaning rule. If you do not have a skimmer in your pond, you may find that your biofilter is doing two jobs: biological and physical filtration. Our first piece of advice would be to install a skimmer, but, until then, only clean your biofilter when absolutely necessary to keep it running, and do so using the process described above.