Fluval FX2/4/5/6 Bio-Foam+ 2-Pack

Fluval Bio-Foam doubles as mechanical and biological filtration, purpose-built for FX2, FX4, FX5, and FX6 canister filters.

The Fluval FX2/4/5/6 Bio-Foam+ gives nitrifying bacteria a home to colonize as part of your tank's biological filtration — see our guide to the Nitrogen Cycle for how this fits into overall water quality.

The Fluval FX2/4/5/6 Bio-Foam+ is a replacement part for keeping your filter running at full performance — see our guide to choosing filter media for how media and hardware work together in a filtration system.

Specifications

Fluval item #A239, UPC 015561102391. Bio-Foam+ for FX canister filters, supplied as a two-pack.

What Fluval claim for it: a mechanical and biological medium in one — a dense structure that traps small particles, and an intricate porous network that gives beneficial bacteria a large surface area to colonise. Rated for freshwater and saltwater.

Compatibility

FX2, FX4, FX5 and FX6. That is Fluval's own compatibility statement for A239 — all four FX canisters. Our product title says FX5/6, which understates it: if you run an FX2 or an FX4, this is still your foam.

Do not confuse it with plain Bio-Foam (A228, a three-pack listed for the FX4, FX5 and FX6), which is a mechanical pad on a different replacement schedule.

Setup & Use

Fluval's FX chart for this medium: check and clean it every three months, and replace it every six. That is the schedule for Bio-Foam+ specifically; plain Bio-Foam is on a different clock (clean monthly, replace half the quantity every six months), so do not carry one interval across to the other.

Never change all the media at once. Fluval repeat this in every manual: the beneficial bacteria live on the media, so staggering replacement is what keeps the biological filter alive through a service. Rinse media in water taken out of the aquarium — never under the tap, and never with soap or detergent.

Where it sits in the flow. On an FX the water moves to the bottom of the canister first, then rises through the foam pads before passing down through the media trays. The foam is doing the coarse work before anything else sees the water, which is why it loads up faster than the media above it.

Close the valves, unplug, then drain. Before any part of a canister filter comes off, Fluval's sequence is: turn the IN and OUT valves to the closed (horizontal) position, unplug the pump, then disconnect. The canister sits below the tank and is full of water — opening it in the wrong order empties it onto the floor, and on an FX4 or FX6 that is fourteen to twenty litres.

Safety & Precautions

Close the valves, unplug, then drain. Before any part of a canister filter comes off, Fluval's sequence is: turn the IN and OUT valves to the closed (horizontal) position, unplug the pump, then disconnect. The canister sits below the tank and is full of water — opening it in the wrong order empties it onto the floor, and on an FX4 or FX6 that is fourteen to twenty litres.

Unplug everything in the tank before your hands go in the water. That is Fluval's own instruction and it covers every appliance in the aquarium, not just this one. Grasp the plug and pull it; never yank the cord.

A spare is only as safe as the unit it goes into. Fluval's standing instructions still apply to the filter itself: the power cord cannot be replaced or cut, a unit that has been dropped or shows abnormal leakage should not be put back into service, and repairs go to an authorised service facility rather than a kitchen table.

What's in the Box

Two Bio-Foam+ pads. Fluval's own pack format for A239. Their maintenance chart replaces Bio-Foam+ every six months, so a two-pack is a year of servicing if you stagger them — which is exactly what Fluval ask you to do.

Returns & Replacement

Returns are accepted within 7 days of delivery, provided the item is unused and in its original packaging. Manufacturer-sealed items cannot be returned once the seal is broken, and sale-priced items are not refundable.

If your item arrives defective or damaged, message us on WhatsApp with your order number — or email us, if you would rather — and we will replace it. Approved replacements are delivered within 3 to 5 business days. Transit damage is covered by insurance on every shipment. If tracking shows delivered but nothing reached you, tell us within 72 hours, which is the reporting window Indian couriers allow. Damage caused during installation or use is not covered; replacement spares for such cases are chargeable.

Full terms are on our Cancellation & Returns page.