Is It Necessary To Change Filter Sponges/media?

I have a fluval U2 filter and it says in the instruction manual to change the cartridges every two months. If I do this, isn't it removing all the good bacteria? To be honest, my filter is a little brown on the inside because my mopanI wood is still releasing tannins but I know that's not harmful. I just want to know if I should replace the insides of my filter (sponge/cartridges/media).

 

I'm not familiar with that filter, but generally you do not want to replace the cartridge unless it is totally falling apart, since as you stated that's where the bacteria lives. But you can swish it around in a bucket of dirty tank water to clean out the gunk.

The brown from the tannins should not cause any problems as far as I know.

 

I don't know. But something I do know is that replacing the filter cartridges will not remove ALL of the bacteria. All though you might not want to do a water change and replace cartridges at the same time. wait I just read all mighty mod jdhefs post. Am I wrong? cause I am terribly sorry if I am. I try to give good helpful info.

 

I suspect that most (if not all) filter manufacturers recommend overly pessimistic timeframes for media placement. I think it's just a lot of aggressive marketing mumbo jumbo designed to increase sales of their filter media.

jdhef is right. Replace it when the filter media (e.g. the sponge or porous pellets) start disintegrating. Replace it bit by bit to minimise disruption to your cycle. Give it a good swirl in a bowl/bucket of old tank water or conditioned tap water to remove any debris during regular maintenance.

But something I do know is that replacing the filter cartridges will not remove ALL of the bacteria.

It won't, there'll still be bacteria on the substrate, decorations, walls, water column. But the filter media contains the highest density of bacteria due to biofilm formation on porous surfaces. Replacing all the filter media at once is likely to destabilise a cycle and introduce a "waiting period" before sufficient bacteria reproduces to accomodate the tank's ammonia production rate.

 

The vast majority of bacteria lives in the filter media, so removing the media would disrupt your cycle. There is very little bacteria in the water column, so performing a water change should have no impact on the cycle.

 

Almost no bacteria lives in the substrate due to the fact that there is little/no water flow/oxygenation in the substrate, deeming it a relatively unsuitable environment.

If your sponge starts falling apart, chuck both sponges in a bucket with a large airstone & leave them for two weeks. Change the water everyday in your main tank until the two weeks are up.

 

Well I guess my filter is fine since i've had it for almost a year and none of my fish have died so I'll stick with it for a while
Thanks guys

 

I would rinse the Foam Pads and BioMax in old tank water and put back into the filter. If you are using the U2 Poly/Carbon Cartridges in there as well, I would think you could replace those without worry. Most BB will live on your Bio-rings and some on the foam pads.