Fluval Poly-max U3 Cartridge
Specifically designed for the Fluval U3 filter, the U3 Poly-Max Cartridge helps control green water and unsightly algae growth by trapping and adsorbing phosphate, nitrite and nitrate.
Chemical filter media
Produces crystal clear water, reduces odor, and creates ideal conditions for fish and plants
Helps reduce overall aquarium maintenance
Suitable for freshwater, saltwater or reptile environments
Convenient 2-pack format
| Specification | Details |
|---|---|
| Filter Type | Poly-max Cartridge |
| Compatible With | Fluval U3 Filter |
| Media Type | Chemical |
| Target Contaminants | Phosphate, Nitrite, Nitrate |
| Usage Environment | Freshwater, Saltwater, Reptile |
| Pack Size | 2-Pack |
FAQ
Can the Fluval Poly-max U3 cartridge be used in a saltwater aquarium?
Yes, the U3 Poly-max Cartridge is suitable for saltwater environments.
How often should the cartridge be replaced?
Please contact customer service for replacement frequency guidance.
Does this cartridge help with algae growth?
Yes, it helps control green water and unsightly algae by adsorbing phosphate, nitrite, and nitrate.

Sean Lawrence –
The filter cartridge works well in my freshwater tank. I noticed less algae growth after installing it. Water clarity improved significantly. Easy to replace and fits perfectly with my Fluval U3 filter.
Austin Dyer –
I’ve used this cartridge for a few months now. It helps reduce odors and keeps the water cleaner. The 2-pack is convenient for regular maintenance. Slight improvement in plant health.
Charles Peake –
Great product for controlling phosphate levels. My tank has been much clearer since switching to the Poly-max cartridge. Works well in both freshwater and saltwater setups.