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carbon filters


recycled oldy

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My post of 15 May under community/freshwater, queried the use of carbon/charcoal filters in a planted tank. Disapointingly it only received two comments. One facetious nonsense, the other non-commital.

This is a genuine request for sensible comment as there is definite contradiction between trade articles. Would the experienced fishkeepers out there use carbon filters in a planted tank or do they recommend against it?

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The main role of activated charcoal filters is to remove toxins, and chemicals. In a planted tank the charcoal may also remove humic substances which provide nutrients and CO2 for plants. It can be used to combat a heavy algae infestation by removing allelochemicals ( chemicals released by one plant/algae which suppresses the growth of another ), and dissolved organic compounds which provide iron to the algae.

So, activated charcoal is not recommended except as a treatment.

Reference: Ecology of the Planted Aquarium, Dr Diana Walstad, Echinodorus Publishing, First edition 1999

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Carbon is not meant to be a long-term filter media, although many people use it thus. As GrahamC has mentioned, it is used to remove toxins and medication after treatment then thrown away. If you use carbon for an extended period of time, it will eventually reach its maximum filtering capacity and start purging the toxins back into the water. Research on hole-in-the-head disease in cichlids have shown that it can be caused by extended use of carbon.

So, carbon is only necessary for certain situations and even then only a few days is required.

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Over a period of about 40 years I have always used the charcoal supplied with many filters for any other use other than in the filter. I have not used it in filters in bare tanks, lightly planted or heavily planted tanks with or without added ferts. The first thing I do with it is throw it out. Hope that answers your question.

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Useful tool for short periods of time (~month) , for a specific purpose (examples mentioned above).

Other than that, don't bother.

Arguements about carbon "leeching" rage on, my experiences lead me (and other experienced fisho's) to believe that it DOES leech, though others will fervently deny this. There are papers and scientific reports on both sides too...

Regardless, the use of carbon is probably best kept to a short time frame, especially for purpose of chemical removal...

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i have not bothered to use them since i was a beginner. if i want to remove chemicals from the water i would just do a couple of large water changes over a few days, in my thinking that would be far quicker and effective than waiting for carbon to absorb it. to get crystal clear water you need to remove the physical particles from it so mechanical filtration is the answer for that. to achieve that with an AR980's filter system you need good filter wool and replace it regularly. i would look into putting a course and fine pad in each filter box which will catch most or all of the particles being circulated.

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And in case anyone is thinking of it, not just teenagers who overdose; we'd restrain them, put a large tube through their nose into their stomachs, do lots of 100% water changes and top it off by pouring a slurry of activated charcoal into the person's stomach. I don't recall anyone sucking on those tubes to empty the stomachs using siphon action though! :slfg:

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Thanks smidey, I did that very thing this morning, Charcoal binned, two thicknesses of Aqua fine filter wool with the coarse black filter on top and 15% water change.

regards

make sure the water can flow through fast enough so it doesn't flood. A good way to safe guard against that is making the pads a little smaller than teh box so any overflow can escape down the side of the sponges.

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making the pads a little smaller than teh box so any overflow can escape down the side of the sponges.

The problem with that, is that the water will always find the easiest route, which would be around the pads, rather than through them, which is really what you want for filtration...of course...

just monitor it, if you get blocking problems, reduce to one layer of foam or change out for a less dense foam pads...

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The problem with that, is that the water will always find the easiest route, which would be around the pads, rather than through them, which is really what you want for filtration...of course...

nah totally disagree. the water landing on top of the pads does not magically run across them as there is nothing to prevent it, it still soaks through the pad as fast as it can. as time goes on particles clog the pad which can reduce the soakage rate below the rate of supply at which point it needs an alternative route so the gap allows the over flow to escape. it's a good safety measure as i had an overflowing problem with the same style of filtration system when i added extra pads and flow.

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nah totally disagree. the water landing on top of the pads does not magically run across them as there is nothing to prevent it, it still soaks through the pad as fast as it can. as time goes on particles clog the pad which can reduce the soakage rate below the rate of supply at which point it needs an alternative route so the gap allows the over flow to escape. it's a good safety measure as i had an overflowing problem with the same style of filtration system when i added extra pads and flow.

Hey, I'm just repeating what I was told when I got both my Aquaculture qualifications...

If it were free-running water, in a trickle-tower type setup or similar, not in an enclosed box, You'd be right, as the water would drain away from inside the sponge as more came onto it, and you could control the drop of the water right into the pad. as you point out, this is when the pad is new and clean, as it fills with crap, you'll get more and more skeeting around the edge...

In a pressurized canister, the whole pad, and everything around it, is already full of water, the force the pump is creating to pull the water through will cause the flow to run around the edges of the pad, rather than through it...

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i was referring to a trickle filter in a AR980 which recycled oldy has and this is from my experience, i didn't read it or get told about it.

when the pads or wool on the trickle filter clog the water (as you have stated about going to least resistance) then moves towards the edge but soaks through the next clean part of the pad until it clogs and gradually heads the flow further toward the edges as the pads or wool are too course for it to simply run over. eventually it gets to the edge so if there's a gap it will still flow through the filter system, if not it will raise the water level and eventually flood the hood out the end or sides of the box depending on which is lower so having a small gap is a good insurance measure against flooding.

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to achieve that with an AR980's filter system you need good filter wool and replace it regularly. i would look into putting a course and fine pad in each filter box which will catch most or all of the particles being circulated.

Info like that helpful...

I didn't know the context...

:cofn:

seek and you shall find :D

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