The Fluval FX series is considered by many to be one of the best canister filter brands currently available on the market. The Biohome Ultimate is also one of the most recommended biological filter media that you can use for your fish tank.
So, if you are planning to use both products, how much Biohome Ultimate can you add to the Fluval FX4, FX5 and FX6?
You can find out in this guide at Aquarium Blueprints.
Quick Summary
If you remove the half-sized media basket, Bio-Foam and Carbon Foam, the Fluval FX4 Canister Filter should be able to hold around 3.4 kg (or 7.5 lbs.) of Biohome Ultimate.
The bigger Fluval FX5 and FX6 Canister Filters can hold more at approximately 5.1 kg (or 11.25 lbs.) of the Ultimate filter media.
About the Fluval FX4, FX5 and FX6 media baskets
The Fluval FX5 and FX6 each comes with 3 full-sized media baskets while the FX4 comes with 2.
Furthermore, the FX4, FX5 and FX6 each includes a pair of half-media baskets.
How much Biohome Ultimate can you add FX4, FX5 and FX6?
You should be able to add around 1.7 kg (or 3.75 lbs.) of the Biohome Ultimate filter media for every full-sized media baskets. This is assuming that you remove the half-media basket to free up more space in the full-sized media baskets and keep the foam on the outer ring.
While you can also remove the foam from the outer ring in order to add more Biohome Ultimate, we don’t recommend doing so as you will need mechanical filtration to keep the microscopic pores of the biological filter media from getting clogged up.
If the pores of Ultimate get blocked, then the beneficial bacteria living inside won’t be able to access the tank water in order to consume ammonia, nitrites and nitrates. Eventually, there will be a die-off, causing a disruption to the biological filtration of your tank.
If you don’t use mechanical filtration on the outer rings of the media baskets, then the Biohome Ultimate will clog up a lot faster.
The foam on the outer ring should be good enough to catch debris from your tank water. You don’t really need the Bio-Foam with these filters. In most cases, you don’t need the carbon foam unless you want to use the chemical filter to remove medicine, odors and discolorations in your tank.
Since the Fluval FX4 Canister Filter only has room for two full-sized media baskets, it can hold up to 3.4 kg (or 7.5 lbs.) of Biohome Ultimate.
For the Fluval FX5 and FX6, you will have three full-sized media baskets. As a result, these bigger canister filters can hold a maximum of around 5.1 kg (or 11.25 lbs.) of the Ultimate filter media from Biohome.
What is the recommended amount of Biohome Ultimate for your tank size
1.7 kg (or 3.75 lbs.) of Biohome Ultimate should be good enough for every 40 gallons to 50 gallons (or 160 liters to 200 liters) of tank water.
If you have a heavily stocked tank, then 2.4 kg to 3.2 kg (or 5.29 lbs. 7.05 lbs.) of Biohome Ultimate is recommend for every 40 gallons to 50 gallons (or 160 liters to 200 liters) of tank water.
In addition to these canister filters, you can also add Biohome Ultimate directly in your tank if you need more room.
