Preserving your beneficial bacteria - A note concerning filter changes

Resist the urge to scrub it clean! Sponge filter media are a great home for established beneficial bacteria colonies in your water garden. 

So it's about time to change our filter media. The good water test results from yesterday are encouraging and I'd rather change these guys out before ammonia and nitrite concentrations start heading south again. I talked with the friendly lady with the haircut resembling a German dominatrix over at Austin Aquadome today and she gave me some good advice.

You like fish?? I'll show you fish!! Whip! Smack! Oww!

First of all, the filter media is where your beneficial bacteria colonies grow. These bacteria are essential to keeping the nitrogen cycle in your tank smooth, so if you simply toss out your old filters and replace them with new ones, all your hard work is gone and your ammonia levels will start poisoning your plants and fish. It's best to replace only one filter component at a time, either the carbon or the biological, so that some bacteria still remain. The sponge, a physical filter, should be used until it literally falls apart. Never [NEVER!] rinse it under tap water since the chlorine and other city chemicals will kill your ammonia-eating amoeba friends. Just rinse and squeeze it using the reservoir water. Don't worry if it's a little dingy looking; no one will see it way down inside the canister. And if your mother comes to your house and chastises you for a dirty sponge filter, you need a new mom.