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Discussion Starter · #1 ·
Here's a crazy idea - why not use activated carbon for substrate. We know that Carbon pretty much strips chemical from the water column, including trace elements. My thinking is to use activated carbon loaded with trace and mix with my Flourite black. Am I crazy or does this actually make some sense.
 

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Why would you do it? Just curious, I mean, seriously... why?

You have fluorite black, so you have a good substrate, it's not like you can't find anything to use... and you've already admitted that you're aware that activated carbon can be bad for planted tanks, because it strips nutrients away...

So once again... why?


Okay, so I never technically answered your question... why not do this? For starters, because activated carbon is very light and messy, and will just float around your water column when things get stirred up. It's also much too fine to mix in with your fluorite, and you will end up having two distinct layers in your substrate after the carbon settles beneath the fluorite. It's also BAD to strip nutrients away from your water column in a planted tank. I'm sure there are more reasons but that should get you started. :)
 

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No, I'm aware that he was talking about saturating it with nutes. It still begs the question... why? Why not put those nutrients under the fluorite and save the carbon for a breeder or quarantine tank or something?
 

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Discussion Starter · #6 ·
Carbon comes in many different grain sizes. There are ones that look very similar to Flourite black. My reasoning for using saturated carbon is that I don't have to dose trace via the water column - it'll be available via the substrate. Secondly, it'll be more uniformly distributed than using root tabs. Just a thought...
 

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Discussion Starter · #7 ·
YikesJason raised a really good point regarding CFC. Flourite is desirable because it has high CFC. I'm wondering if carbon has even higher CFC than Flourite.
 

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Discussion Starter · #9 ·
Furthermore, by not being careful when you uproot plants, you sometime run the risk of disturbing your root tab and releasing tons of unwanted nutes.
 

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I have a few loose pieces of carbon in one of my tanks, and whenever something (like my hand, the python, a cory, etc) moves past them, they float halfway across the tank before settling down.

It's not so bad if there are only a few pieces in the tank, but if the entire floor was covered in carbon, it would make a huge mess all the time.
 

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Activated carbon works by "grabbing" and holding contaminants/organics/impurities/etc. Once the carbon is "full" it will simply not "grab" anything else.

I work in an industry that uses activated carbon to filter volatile organic compounds for air sampling. Once the filter is used for so long (all or most pores get filled or blocked) it simply allows the VOCs to pass right through. If you were to remove this carbon filter to a fresh, clean environmental and draw a clean sample through it does not then release the VOCs it has been saturated with.

If activated carbon just released it's captured impurities then it would not be a beneficial media is used for filtration.

I am thinking that once you have saturated your carbon with nutrients you have essentially created grains of sand that now contain nutrients that are impossible or very difficult for plants to obtain.


 

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A few reasons not to use only carbon as substrate. Assuming you have nice grain size, not dustlike material or big chips.

1. Price
Maybe you found it dirt cheap. Years ago I bought a 5 gal. bucket off ebay for $25. Finding such a deal is hard.

2. Very light
Holding down the plants will be an issue. Easily uprootable. Better not have shrimp in the tank.

3. Carbon can spontaneously release what it has absorbed.
I'm not completely convinced that can really happen but I think I've experienced it myself.

4. Carbon absorbs a long list of chemicals. They basically get wedged in the porous structure of the carbon. N, P, Iron, Traces and many many more. How good is carbon about giving them to the roots (Cation Exchange Capacity or CEC)? Bacteria is involved in this process and they can certainly find a lot of surface area to live inside the carbon. Sounds like a winner. But different carbons have different absorbtion properties. So the carbon CEC (if any) will depend on the kind of carbon, you can't say "it's gonna be good or bad" for all carbons. Still I think if it's within some range it will be fine.

Experiment if you can, why not.

--Nikolay
 

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Of course I have an opinion too. The biggest problem with charcoal as a substrate would be the light weight. I suspect most charcoal is barely heavier than water, so that would likely be an insurmountable problem. But, activated carbon, or charcoal, in the substrate would do no harm to the plants. In fact many planter mixes for terrestrial plants contain activated charcoal, because it is a good component of a planter mix. It does not spontaneously release the materials it adsorbs. I suspect, but don't know for sure, that its ability to adsorb organic compounds would be an asset in that it would hold those compounds where plant roots could pick them up, just as a high CEC material does.

But, the light weight would be a killer to deal with.
 

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you notice the higher CEC a substrate is claimed to have, the lighter it is, yeah? SMS/Turface is claimed to have a very high CEC ratio. I'd assume if tests were run on both, it would have nowhere NEAR as high as most types of activated Carbon. Then again, it is heavy enough (if barely) to hold down most plants.

The good thing is that after a while, SMS gets full of mulm, etc and is a lot easier to deal with. In fact, I'd say everything about SMS gets better with time. Maybe the same would be true with activated carbon. You could end up with a fantastic substrate, but either it'd be months before it'd be "good" or you'd have to go about saturating it with ferts for a long while before it resembled anything near a substrate. (and I would have my doubts as to it releasing its contents as readily or evenly as you're hoping for, to not have to dose)
 

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Don't mean to hijack the thread but, I do have a question about discarded carbon. The last time I used it you take it out of the filter and it smells VERY fishy, it makes me wonder if it would be a great fertilizer for an outdoor garden. Any thoughts with all the stuff it absorbs?
 

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Throwing it in your garden or compost pile shouldn't hurt as long as it's not full of medications, just the normal aquarium wastes. I use my old water from water changes to water my vegetable gardens. Plants like ammonia; it's just bad for fish. I don't know if the carbon would be a fertilizer--you'd have to put in large quantities on a regular basis anyway. But it can't hurt.
 
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