Large Foam Sets 43" x 21" CMF

To maintain effective water filtration and lengthen the life of your filter, replace your old foam filters.


For almost all sizes and types of box filters, we provide filter foam sets.
Profiled foam is provided in groups of three, each about an inch thick.


Fine (Green), Medium (Black), and Coarse (Blue)


These filters are made in the UK from premium reticulated polyether foam that can be trimmed to size for a big, cost-effective surface.


To provide sparkling water quality, these filters can be used in conjunction with additional filter wadding.
For sparkling water quality, high-quality sheet foam may be cut to any size, providing a large, affordable filter surface. It can also be used in conjunction with filter wadding.


There are 3-piece foam packs that fit nearly all sizes and types of biological box filters.
Each set is typically given with three distinct dimpled foam grades.


The typical sizes range from about


17″ x 11″,\s 25″ x 18″\s 43″ x 21″.

Is delivery free?

We offer free delivery on the majority of our products over £50. This excludes live fish and bespoke filters. Delivery to UK mainland addresses is £3.95 as standard, or £6.95 for express.

How do I return a product?
Get in touch via email or phone and let us know your problem, we will then help as much as possible. A postage address will be given for you to return the product back to us, and postage will be refunded where applicable to our terms and conditions, which are in line with consumer rights.

At Steel City Koi, we offer a wide range of safe and secure payment options when shopping with us.

Accepted payment methods:

Debit/Credit Cards (Inc American Express)

BACS (for faster dispatch of products) please get in touch for this

Cash upon collection *only for live fish

Pay Later options currently include Klarna and Clearpay