Hi, I am an older guy and have been keeping fish for a few years off and on.

[Billybong1]

Can anyone tell me an approximate amount of charcoal I should put in my filter basket. I use a Fluval 305. Thanks.

 

[jaylach]

Personally I would not add charcoal at all. Add more filter media instead if possible. Charcoal really does nothing except pad the manufacturer's wallet.

Charcoal DOES have its use but only to remove some medications after treatment and sometimes can help clear cloudy water. In both cases it is a specific and temporary use. In normal situations it does nothing to help the tank.

 

[gwand]

Here's a breakdown of its pros and cons:

Pros of putting Activated Carbon in a Freshwater Aquarium Filter:​

• Removes Odors: Activated carbon is highly effective at eliminating unpleasant smells from the tank, keeping the water smelling fresh.
• Improves Water Clarity: It absorbs dissolved organic compounds that cause discoloration (like tannins from driftwood) and cloudiness, resulting in crystal clear water.
• Removes Harmful Chemicals: It's excellent at removing chlorine and chloramines from tap water, which are toxic to fish. It also effectively removes phenols and other dissolved organic waste.
• Removes Medications and Residuals: After treating fish with medication, activated carbon can be used to remove any leftover chemicals from the water, preventing long-term negative effects on fish.
• Helps Control Algae: By removing excess nutrients and organic materials that fuel algae growth, activated carbon can indirectly help reduce algae outbreaks.
• Affordable and Easy to Use: It's a relatively inexpensive filter media and is easy to add and replace in most filter systems.

Cons of putting Activated Carbon in a Freshwater Aquarium Filter:​

• Becomes Saturated Quickly: Activated carbon has a finite capacity. Once its pores are full of adsorbed impurities, it loses its effectiveness. This typically happens within 2-4 weeks, depending on the tank's bioload.
• Needs Regular Replacement: Due to its saturation, activated carbon must be replaced regularly. Failing to do so means it's no longer filtering effectively and is just taking up space.
• Does Not Remove Ammonia, Nitrite, or Nitrate: It's crucial to understand that activated carbon does not remove the primary nitrogenous waste products (ammonia, nitrite, and nitrate). These are handled by biological filtration and regular water changes.
• Can Remove Beneficial Trace Elements: While it removes harmful chemicals, activated carbon can also adsorb some beneficial trace elements that are important for fish and plant health. Regular water changes typically replenish these.
• May Leach Phosphates (in some lower-quality brands): Some lower-quality activated carbon can leach phosphates into the water, which can contribute to algae growth. Look for acid-washed or phosphate-free carbon.

 

[GaryE]

We used charcoal in the sixties and seventies because we didn't change enough water, and our tanks stank. Once we began to do 25-30% or more weekly water changes, charcoal became obsolete. It's still sold, because it doesn't last long and it removes money from your pocket. Aquarium companies aren't fools. But we no longer need it.

 

[Back in the fold]

I beg to differ from my esteemed colleagues . Fill about a third of the filter basket with a good aquarium charcoal . There is always something in the water it can remove to your benefit and your fishes . If you don’t want to throw your carbon away then boil it for a half hour and use it again . That’s an old time aquarium keepers trick . Pay no attention to these new wave naysayers .

 

[fishorama]

I wouldn't worry about removing the carbon. After it quits removing "stuff" in several days, it can still work as a place for beneficial bacteria to grow. You don't need it regularly or to change it often.

Do you have a specific reason for using carbon? Like others, I only use it to remove meds, etc. Weekly water changes will fix many issues & it's a good habit to get into.