Charcoal longevity (small, light, cover, place)

[jambo101]

Bought 3 small bags of charcoal to replace whats in my filter, problem is when i took my canister filter apart i discovered it required 6 small bags of charcoal so i just rinsed off 3 of the old bags and re-installed them with the 3 new bags.
Got to thinking how long does charcoal last? can it just be rinsed off once in a while and re-used as filter medium? how does charcoal wear out or lose its effectiveness?

[BrianH]

I think with AC people are going to tell you different things from a few days to a few months is all it will last. Id imagine it would depend on how big the tanks is, what you have in it and how long you go between each water change. The dirtier the water, longer stints between changes etc would shorten the life of it I would say. When I used AC i changed it once a week. Somebody else on here may know different though.

[BrianH]

You cant just rinse it off either as it absorbs everything.

[Aredhel]

Do you even need charcoal? Is the fish load in your tank high? Do you have wood that's leaching tannins and discoloring the water? Charcoal is mostly useful for removing unwanted organics, but if you're doing frequent water changes and don't have the tank overstocked you may not need it at all.

One of the nice things about canister filters is that they allow great flexibility in terms of what media you can load in them. I only put charcoal in my Eheim if I've had to medicate the tank; after the treatment is completed I'll add charcoal to adsorb the medication and get it out of the water. The rest of the time my filter just contains floss and noodles.

[jambo101]

I have a 45gal tank with a dozen tetras.

[Aredhel]

That's a pretty lightly stocked tank. If you are doing regular weekly water changes, the addition of charcoal to your filter is probably optional (especially if it's a planted tank).