Filter For 60 Litre (Approx 15 Gallons)

[KittyKat]

Biomax is Fluval's bio media, it normally has a much higher surface area than sponges and works purely for biological filtration. In other words, most of the bacteria will live there. If bio media is used, it is safer to replace some, or sometimes even all (as in some external filters), sponges. You should still treat all sponges, except polishing sponges, as bio media, of course.

What you have done is fine. Use carbon as you want to

 

[nessar]

Is it better to use my own loose carbon or the sponges?

And do you need to replace biomax and if so how often? The leaflet says you do but then it also says you need to replace sponges, which I know you dont as long as they're not falling apart.

 

[OldMan47]

The biomax will last a good long time without replacement. As you have already surmised, sponge type filters last as long as they do. Until they fall apart, they are fine quality filters. Use as much as you can from your old filter in that new filter's flow path and your new filter will quickly become cycled, which is what is truly essential.

 

[KittyKat]

Is it better to use my own loose carbon or the sponges?

I imagine that your own will last for much longer and be more effective (higher surface area for same volume).

And do you need to replace biomax and if so how often? The leaflet says you do but then it also says you need to replace sponges, which I know you dont as long as they're not falling apart.

It is considerably more important to *never* replace the bio media than the sponges, if both are used. It should last for 20+ years anyway

 

[JoshuaA]

With the U2 it is always good practice to remove the biomax cartridge and give it a good swish around in used tank water when cleaning though. That cartridge can clog up if dirt has bypassed the filter sponge.