External Filter: Using Charcoal, Is It Toxic?

Q: I have external filter and would like to use charcoal in it? Will do so be toxic in the long term?

Activated charcoal is used to remove toxic chemicals such as ammonia in the water. It acts like a sponge in this respect. However, there’s a limit to how much chemical it can absorb. Once the limit is reached, it won’t be effective anymore. Some people believe that since the toxic chemicals are not chemically bonded to the charcoal, they may yet again leach into the tank over time. It is hence good practice to replace the charcoal every two to three months.

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