Fluval Foam Filter Block for Spec/Evo/Flex/Betta Aquarium Kit

The Fluval Foam Filter Block is the genuine replacement mechanical foam for the rear filter chamber of Fluval's popular nano aquarium kits. As water passes through, the open-cell foam traps debris, uneaten food, and waste before they cloud your tank, keeping the water clear and protecting the biological media behind it. Keep a spare on hand so a routine swap is quick and mess-free. Browse our filter media and cartridges for the rest of your maintenance kit.

Features

• Genuine Fluval replacement foam block
• Open-cell foam traps large and fine particles for mechanical filtration
• Protects biological and chemical media and keeps flow strong
• Rinse in tank water to reuse; replace when it starts to break down
• Safe for freshwater and saltwater aquariums

Compatibility

• Fluval Spec, 2.6 US gal / 10 L and 5 US gal / 19 L
• Fluval Evo, 5 US gal / 19 L
• Fluval Flex, 9 US gal / 34 L
• Fluval Flex 2.0, 9 US gal / 34 L
• Fluval Betta, 2.6 US gal / 10 L and 6 US gal / 22.7 L

For the larger Flex 15 gallon kit, use the Fluval Foam Filter Block for the Flex 15.

Specifications

Recommended Pairings

• Fluval Flex 2.0 Aquarium Kit — the nano kit this foam block keeps running clean.
• Fluval Flex 2.0 Poly-Carb Cartridges — pair the foam with chemical filtration for polished water.
• Water care and conditioners — keep spare media and treatments stocked.

Frequently Asked Questions

How often should I replace the foam? Rinse it in old tank water at each water change to clear trapped debris, and replace it when it starts to fall apart or no longer springs back, usually every few months.

Should I replace all my media at once? No. Swap the foam separately from your biological media so you never remove all your beneficial bacteria at the same time.

Will it fit my Fluval kit? This block fits the Fluval Spec, Evo, Flex 9 gallon, Flex 2.0 9 gallon, and Betta kits. For the Flex 15 gallon, use the Flex 15 foam block.

Can I use it in saltwater? Yes. The foam is inert and works in both freshwater and marine setups.