Need advice on changing filters

[Chirp]

It's been about 2 months since setting up tank. I'm assuming in the next couple of months I have change the filters on the tank. My question is:
1. When should I do it?
2. How do I change the filters without losing the beneficial bacteria?

I have a aquaclear 20 HOB so it has a coal filter, a sponge filter, and the bio filter. I'm assuming that the coal and sponge filters can be switched out without any problems, but how about the bio filter? should I keep the old bio filter in the aquarium for a week so that the new biofilter has time to grow enough bacteria?

 

[BHead707]

what i would do is take only one out at a time, the main bacteria will be on the bio and the sponge provides a ton of surface area for the BB as well. I wouldnt replace them until they are literally falling apart but if you can space the two apart a few weeks it would elp.
also you could do as you said and place the new media in the tank for a little while to seed it

 

[blert]

Just rinse the sponge and bio in old tank water when you do your PWC. They will both last a long time, you shouldn't replace them until they are falling apart. As for the carbon, ditch it and add another sponge or bio. The carbon is handy for removing meds and colors and odors but other than that it lasts about a week and is a major money waster.

 

[Kainen]

And if you do have to eventually replace the bio part what i do is remove the carbon or what ever you have replaced it with before and move the old bio down to where the carbon was and put the new bio on top so the water flows from old bio to new making for fast seeding not sure this is neccessary but had good results for me

 

[Mr. Green]

I have two sponges in my Aqua Clear and the Bio Filter. My plan is if a sponge needs replaced, change one at a time and leave an established one in. I agree to get rid of the carbon unless you need it for something specific.