# Aquarium Charcoal as Substrate Question



## Kahuna (Nov 23, 2008)

What would happen if a person used aquarium filter charcoal for their substrate i have tossed Lbs and Lbs of it away, can old or new filter charcoal be used as substrate?

I hope this is not to silly of a question i have wondered about it for a while.


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## Alasse (Jul 23, 2008)

I would not use it as substrate. Once charcoal is 'full' it leaches the bad stuff back into the water. This is why carbon is recommended to be changed regularly


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## TheCryptKeeper (Mar 9, 2008)

Welcome to the forum.. you will find a wealth of knowledge here.. most is free.. but mine is not.. so have the money wired by the end of that day :hihi:


curious as to why you would want to use the charcoal. because of the grain size and color? there are almost unlimited options for substrate now available for purchase.

also if you find something that you would like to use.. you can always do a forum search or look through the titles here. Let us know if we can help in any other way.
good luck roud:


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## Kahuna (Nov 23, 2008)

Thank You very much for the Welcome!

Ok, I got to wondering what if i could recycle my old filter carbon as substrate instead of pitching it out, but i dont know if it would be harmful or not so i thought i would go to a forum were there are people very educated and experienced to ask! 

I know it may be a very silly question to some but i guess i am a very silly girl but it is still something i am curious about.

If it would work i would rather save it up and reuse it as substrate then throw it away after all its already paid for and i do like the color and size.

If it would not harm anything, i would like to save mine up and reuse it as substrate instead of buying other substrates when i have this for basicly free.

*My questions:* 

*First one:*

_#1 has anyone ever tryed it?_ 

*If in fact it is harmful:*

_#2 How would it harm the tank?
#3 How would it harm the fish?_

*If it is not harmful:*

_#4 Would it work in a unplanted tank?
#5 Would it work in a planted tank?_


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## Hoppy (Dec 24, 2005)

If you are accumulating that much charcoal you are using far more than is needed for a filter in a planted tank. At most charcoal is useful for removing the brown color from tanins in the water, removing medications added to the water for fish ailments, and perhaps during the initial startup of a new tank. Other than that it serves no useful purpose in the filter for a planted tank.

I haven't tried it as a substrate, but I see no reason why it wouldn't work, other than its very light weight, which would make planting in it difficult. As far as I know charcoal doesn't contain anything harmful to either fish or plants. It might even help hold some nutrients so they would be accessible to the plant roots. If you decide to try it, I suggest doing so in a small tank, with fish that aren't too expensive. And, be sure to let us all know how it worked.


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## Kahuna (Nov 23, 2008)

Hoppy said:


> If you are accumulating that much charcoal you are using far more than is needed for a filter in a planted tank. At most charcoal is useful for removing the brown color from tanins in the water, removing medications added to the water for fish ailments, and perhaps during the initial startup of a new tank. Other than that it serves no useful purpose in the filter for a planted tank.
> 
> I haven't tried it as a substrate, but I see no reason why it wouldn't work, other than its very light weight, which would make planting in it difficult. As far as I know charcoal doesn't contain anything harmful to either fish or plants. It might even help hold some nutrients so they would be accessible to the plant roots. If you decide to try it, I suggest doing so in a small tank, with fish that aren't too expensive. And, be sure to let us all know how it worked.


Maybe i will try it in a planted 10 gallon and a unplanted 10 gallon at the same time i just dont want to hurt any fish i have almost a 5 gallon bucket full of it. 

I was told i had to change the filter media out every 3 monthes, so i have been YIKES !!! 

BTW, My husband told me that!  he is sooo going to get it when he gets home we use cannister filters and im the one who gets the joy of changing the media and we have 5 tanks. :eek5:


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## lauraleellbp (Feb 3, 2008)

There have been some recent studies linking activated charcoal to HITH/HLLE disease. (Hole In The Head/ Head and Lateral Line Erosion) Not confirmed, but still something to be aware of.

I also would be concerned that it would leech toxins back into the water, and that it would be too lightweight to hold down plants... any time I've had some get into the water column it has a tendency to float. Last but not least, it flakes really easily and can cloud the water (as I've been reminded each time I've forgotten to rinse it off first before putting new charcoal in my filters... :icon_roll)


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## EricSilver (Feb 23, 2004)

I recently resumed the use of charcoal in my filter and wanted to add that it will absorb excess chemicals and dissolved organic matter that plants cannot or do not. And because activated charcoal is so fractured, it has enormous surface area for nitrifying bacteria to populate. Finally, it helps keep the water smelling very fresh (the result of removing the aforesaid chemicals/dissolved organics). 

If you change it regularly, leach-back should not be an issue. And if the tank is *heavily* planted, i.e., a jungle, then charcoal's benefits will not be as apparent. But for moderately planted tanks, it is useful.

As a substrate, however, I have no opinion.


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## PicklezMcNasty (Oct 1, 2013)

*reusing carbon in substrate*

i have re-used spent carbon over the past several years. i usually add it to the substrate that i already have and when setting up new tanks i have went a lil heavy on the carbon. i rinse in cool water as not to destroy anything beneficial and have noticed when i have had to uproot plants, they have healthy root structure. the carbon also slightly increases areation in the substrate and around the root structure by helping to keep the substrate from becoming compacted which allows for more vigorous root growth. as far as the spent carbon leaching toxins into the water, this should not prove to be a problem in a healthy planted tank due to the rate at which the toxins would be re-released into the water vs the rate at which your plants and beneficial bacteria metabolize the toxins. as far as reusing carbon from a tank where medication was added to the water......THROW IT AWAY or add it to a flowerbed! hope this helps!


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## sevenportsOFFICE (Aug 5, 2013)

If the carbon were to get ground down and blown around the tank or go through the filter and blown around the tank, the dust would make a huge mess. IMO, carbon is best left in a bag. Plus carbon has a short life span anyways, the filtering capabilities are short term, as the pores fill up quickly with particles and waste and should be removed once spent. Heck, just leaving carbon out in open air can diminishes it's filtering capability.


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## lochaber (Jan 23, 2012)

I don't really see it being harmful, but I'm also one of those that doesn't feel carbon is necessary in the first place.

Biggest issue I can think of is it being too light to stay on the bottom. Maybe if you mixed it in as part of a dirt layer, or put it on the bottom.

I think a lot of the vivarium folk frequently put horticultural charcoal in their vivariums and grow mixes and stuff, and I think terrariums often have some charcoal in them, so maybe poke around on some of the vivarium/terrarium sites to see how they use charcoal, and try adopting some of their practices for aquarium use.


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