How can you tell when carbon needs replacing

[k1w1y2k]

I have recently get a new (secondhand) tank that came with both an external and large internal filter, both of which have carbon inside them. How can you tell when the carbon needs to be replaced? The filter I'm using is an Aqua One AT882

[LYNDYLOO]

Think it's about every 6 weeks you need to replace it.

[ryanjury]

It depends on how much carbon you have and how much it is actually having to do..

If you aren't using carbon for any specific reason (ie med removal) then I would just remove it and not use it.. It has been a long time (years) since I have used it in any of my 20 odd tanks and I have had no problems or need to use it.

[Aquatopia]

Personally I would not use second hand carbon - you have no idea about whats gone on in the tank beforehand. Also I always thoroughly clean the tank, filters etc when I buy second hand ones and also boil the re-usable media. Carbon is so cheap it doesnt seem worth the risk.

[k1w1y2k]

Thanks, I hear people on here discussing carbon, but have never used it, so I didn't know how necessary it was, and how often it needed changing

[alanmin4304]

I think carbon is realy fantastic stuff. It produces a high class food on a barbi but is just a pain in aquarium filters. I would replace it with something more useful (and have done in my filters)

[Aquatopia]

I think carbon is realy fantastic stuff. It produces a high class food on a barbi but is just a pain in aquarium filters. I would replace it with something more useful (and have done in my filters)

It does have some very valid uses in the aquarium however k1w1y2k, so I would do some research on it and decide what you might want/need it for.

The following paragraphs will give you an idea of what you need to consider;-

"There are conflicting theories arising from the use of activated charcoal in an aquarium. Firstly, some people believe that it should be used permanently. The second school of thought promotes the occasional use of carbon. Personally, I believe that generally it is unnecessary to use filtration over activated carbon continuously. It is best used in response to particular requirements, such as the elimination of toxins, medicinal residue, or pigments such as tannin (given off by wood or peat).

Filtration over activated carbon can prove useful in the long term to treat water containing high concentrations of undesirable substances like chlorine, chloramines, alum, phenols and insecticides and pesticides. Reverse osmosis systems are usefully coupled with activated carbon pre-filters. Used in conjunction, they eliminate chlorinated by-products than can damage the membrane. However, they are not very effective in the removal of nitrogenous by-products. Only the rigorous upkeep of biological filters and efficient biological filtration can help eliminate ammonia, nitrite and nitrate.

The Negative Impact of Activated Carbon

Activated carbon can be criticized for its inability to differentiate between “good” and “bad” molecules. It also fails to retain important trace minerals, including those needed by many hard water fish species and many plants. In reality, the adsorption power of activated carbon is dependent upon the different parameters (e.g. pH of the water) or the chemical form under which the element in question is found. The power of adsorption is limited and it losses its fixation capacity after several days, once it has become saturated. Even worse, it can then release the molecules it had previously extracted back into the water. Therefore, it must be replaced frequently; frequency being dependent on the saturation or concentration level of undesirable elements in the aquarium."

..... credit for the above goes to a cichlid site in aussie 'wessterncichlids.com.au'

[alanmin4304]

In summary, as I said, you are probably better off without it in normal and continuous usage. It also has the ability to store chemicals to the point of getting overloaded then dumping them. I have a number of small internal filters which had carbon and sponge and I have replaced the carbon with more sponge. If you want to remove meds or tanin you can do it with water changes or by adding carbon when required.

[Caper]

Aquatopia quoted:

such as the elimination of toxins

What toxins? For the chlorine and such, wouldn't the chlorine remove take care of those things?

I have hang on the back filters and the cartridges come with the carbon in them.

A question for those who have used carbon and then stopped, could you see a difference in your tanks?

Caper

[Dave+Amy]

I only chuck carbon in when I've finished dosing my tank with Prazi but otherwise there's no point

[oeminx]

A question for those who have used carbon and then stopped, could you see a difference in your tanks?

No not at all, I stopped using around 6mouths ago.

[Aquatopia]

Aquatopia quoted:

What toxins? For the chlorine and such, wouldn't the chlorine remove take care of those things?

I have hang on the back filters and the cartridges come with the carbon in them.

A question for those who have used carbon and then stopped, could you see a difference in your tanks?

Caper

Depending on water quality it could be a whole range of undesirable things, not just chlorine. As others have mentioned it also removes medication once treatment is over, and also tanin discoloration from bogwood. Yes water changes can do this but sometimes not everyone wants to do this as frequently as they might have to in order to keep their water permanently clear.

[alanmin4304]

All undesirables are removed by water changes and some by carbon.

[Aquatopia]

All undesirables are removed by water changes and some by carbon.

I realise that - what Im saying is that there are specific reasons why some people choose carbon nevertheless. For example if I wanted a tank with lots of bogwood in but the aesthetic appearance of crystal clear water without the tanins from the wood I would weigh up the frequency of required water changes against just using carbon to do it for me.

[phoenix44]

I realise that - what Im saying is that there are specific reasons why some people choose carbon nevertheless. For example if I wanted a tank with lots of bogwood in but the aesthetic appearance of crystal clear water without the tanins from the wood I would weigh up the frequency of required water changes against just using carbon to do it for me.

that's pretty much why i use carbon.. ive got a lot of drift wood in the tank, and carbon keeps the water its normal colourless "colour", instead of that yellow which i dont like.

[Aquatopia]

that's pretty much why i use carbon.. ive got a lot of drift wood in the tank, and carbon keeps the water its normal colourless "colour", instead of that yellow which i dont like.

et voila ! that and medicine removal - prime uses of activated carbon. :bounce: