Activated carbon changes

Question
Hi Karen, I love your expertise and your answers are great. I have a 55 gal aquarium. It is the home of 5 clown loaches,5 redeye tetras,5 silver dollars,10 neon tetras, 1 pleco,2 cory, and 7 rasboras. Lots of live plants. I check my water parameters to make sure the water is to the liking of my aquatic friends and perform water changes every two weeks. My question is:How long does it take for activated carbon to lose its effectiveness? Does the beneficial bacteria die when their colony is disturbed? When I perform activated carbon changes I usually do this task in a bucket with the aquarium water.I add about 20% of the used carbon to 80% of the new carbon to  establish a strong colony. But I feel that some of them die during this procedure. What do you advise? TIBORONCITO(little shark)  

Answer
Dear Tiboroncito, (What a unique name!)
How long that carbon takes for it to lose it's effectiveness just depends generally upon how your aquarium is stocked and how polluted the aquarium becomes. Once a month is the general guide but basically it's just that--general. There really is no rule and it all depends on the bioload like I mentioned. I actually don't use much carbon at all. I make up for the lack of carbon with plenty of good water changes and my fish are thriving for it. Carbon as you probably know is excellent for removing tannins that is leached from driftwood should you have any in your aquarium. Sometimes this tea-stained water is very nice looking and represents a lot of amazonian species habitat but this is the one really nice thing about carbon if you dislike amber colored water or your fish won't appreciate the tannins and pH/hardness reducing compounds (like say Brackish water species who prefer harder water for the most part).

Depending upon your filter type, oftentimes changing carbon doesn't harm the biological bacteria enough to lose your entire colony. If your filter contains lots of other media including plenty of sponges or filter fiber, then changing carbon won't be such a risky thing. Also remember as you also probably know is that there is a very large beneficial bacteria colony thriving in your substrate bed. But how you are going about changing your carbon now is very good and I see nothing wrong with it and don't think you should change it.

You are doing a really good job at caring for your fish! Keep up the good work and Happy fishkeeping!!

Best wishes,
Karen~