Pond Filter Foams, Sponges & Sheets

Replacing tired filter foam is one of the simplest ways to keep a pond healthy, as worn or clogged media loses its ability to trap debris and support the beneficial bacteria that break down fish waste. As a general rule, coarser foams are best placed first in the flow to catch larger particles mechanically, while finer or denser foams positioned afterwards encourage biological filtration to establish properly. It's worth replacing foams in stages rather than all at once, so you don't lose the established bacterial colony in one go. If you're unsure which size or density suits your setup, our Pond Filter Size Recommender can help you work out what your filter and pond volume actually need before you order.