Activated Carbon in Planted Tank, Does It Remove Plant Nutrients?

A few years ago, activated carbon in a tank was a staple in the hobby, almost everyone used it, but now, not so much.

Well, I shouldn’t say that, because there’s still a ton of people out there that use it including me in certain situations, but let’s talk about what it is, what it does, and then you can make the decision for yourself whether you want to use it in your aquarium or not.

What is aquarium activated carbon?

You might already be using carbon and you don’t even know it. Carbon is the black stuff that you’ll find in your disposable filter cartridges, behind the sponges. If you’re using one of those filters where you change out that cartridge every month you’re already using carbon.

Carbon is basically charcoal, now this doesn’t mean that you can go out to your grill and grab a couple of your Kingsford briquettes and throw them into your aquarium. No, they process the stuff that you cook with, very different than the stuff that we use in our aquarium.

What does aquarium carbon do?

What carbon does, is absorbs contaminants in the water. Things like tannins and the nasty stuff that makes your tanks stink after a while. It’s an easy product to use, that just helps to keep the tank clean and crisp and keep it from smelling like rotten eggs. It also absorbs chlorine and chloramine, but it’s not something that’s going to replace your water conditioners. You still have to treat your water.

Think of it, like the filters that you change in your home’s air conditioning system once a month, or however often, it picks up the fine particles that you can’t see with the naked eye. If you stick some carbon in your aquarium, it’s gonna do the same thing, and help to pick up those little fine things that you can’t necessarily see. But it doesn’t get anything.

Do I need carbon in my aquarium filter?

There’s a lot of people that look at carbon as something that’s bad for your aquarium and they have good reasons for that.

Does activated carbon remove plant nutrients?

Yes. It will absorb things that you don’t necessarily want it to absorb, like fertilizers if you’re a planted tank keeper and medications.

Activated carbon and fish medications.

The first thing you’ll see on every label of fish medications – “remove your filters carbon”. The reason for that is the carbon does its job and it’ll absorb that medication, making it completely useless.

Don’t use carbon in a planted tank.

Carbon also absorbs a lot of the things floating around in your aquarium, that your plants would typically thrive on. So adding carbon to a planted tank is basically going to absorb all of those nutrients that your plants use to thrive on, and it’ll absorb your fertilizers. So the bottom line is, if you are a planted tank person, take the carbon out, just keep it out of there.

In conclusion, When do you need to use carbon in your tank?

So here is my advice on the use of carbon in your aquarium. It might be a little controversial, but really what is it controversial these days. If you have an aquarium with only fish in it, and you want something that’s gonna help you to keep it crisp and clean, and keep things from smelling like rotten eggs, go ahead and put it in there. But understand, that it doesn’t last forever. When it is worn out, it’s gonna be completely useless. So you are gonna need to change it regularly.

If you’re using a filter with disposable cartridges in it, just swap them out, it couldn’t be easier, that’s kind of why they do it that way. It’s simple, once a month take it out, put a fresh one in and you’re good to go.

But if you’re keeping live plants, or if you have to treat a sick fish or shrimp sickness, keep it out of your aquarium, it’s gonna do more harm than good.