ANOTHER noob question: filter media

[Rbishop]

Activated carbon is only active for about 4 to 6 weeks and needs to be replaced after that. If it is not replaced as it breaks down in your filter it is possible that it can leak all the stuff that it removed back into the tank.
The good bacteria does live in your gravel so when you remove your filter media you are only removing half of the good bacteria. So, I have always been told that on the day you change your filter media it is best to not do a really thorough gravel vac and instead only hover over the surface of your substrate to suck up any left over food or fish waste that has not sunk into the gravel. Do your good gravel vac the next time you change the water.
There are some types of filter media that have lots of surface area for good bacteria to grow on and never have to be replaced. Try looking into these. I dont have a canister filter and it has been a while since I worked at a pet store that sold them, so I cannot remember the names of them. I am sure that someone who does will jump in soon.

Totally false..it can not leach back into the tank what it has absorbed bu chemical bonding..unless you run your tank about 2700 degrees F.

Gravel vacs will not remove the bacteria. Bacteria thrives where ever the best conditions are....food and Oxygen. It is not a fifty fifty split between gravel and media.

Expended charcoal has more surface area for bacteria than most anything readily available.

 

[Tifftastic]

Guess I take back everything I said except for that I think using filter sponges and bio-beads are much better than using the cartridges that fall apart so quickly.

I was told by quite a few people that carbon leaching compounds back into your tank can be a possibility because it doesn't bond very strongly with certain organic compounds.