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Charcoal and Peat
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Gus-Gus
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Joined: 27 May 2003

PostPosted: 2003.09.01(Mon)21:02    Post subject: Reply with quote

Hi. Thanks for the help. For your info, tannins once trapped in the charcoal will NOT leach back into the water. Carbon makes it all inert.
As for me, I will be taking the charcoal out of the water and adding the peat in after that. I did some additional research over the weekend and tannins are exactly what the fish need for their eggs. Tannins apparently inhibit the growth of bacteria and help protect fish eggs thereby increasing their chances of hatching.
Thanks again.
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wetmanNY
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Joined: 24 Aug 2003
Location: NY NY

PostPosted: 2003.09.02(Tue)9:25    Post subject: Reply with quote

Yes, Gus-Gus, I realize that the molecule of tannin won't be released, once it's adsorbed to the carbon. A good point.

But Iwas wondering whether, even stuck to the carbon, that molecule could still exchange its H+ ions for Ca+ and Mg+ ions-- which is how tannins and humins slightly soften and also acidify the water.

I'm no scientist, but thought the experimental technique Tommy suggested sounded like a good one.
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Jak Crow
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Joined: 19 Jun 2003

PostPosted: 2003.09.02(Tue)12:10    Post subject: Reply with quote

I thought the carbon would just help clear the discolouration from using peat, not actually remove the acids.
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wetmanNY
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Joined: 24 Aug 2003
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PostPosted: 2003.09.03(Wed)16:45    Post subject: Reply with quote

hmm. we need a chemist. I'll try to make this simple. The "dis" coloration of the water comes from soluble polyphenols leached from peat, bogwood, oak leaves, teabags etc. Tannin is one kind of polyphenol, but they are a broad class of big organic molecules.

What make phenolic molecules such as humic acids and tannic acid "acids" is that they let go an "acidifying" H+ proton (lowering the 'pH"-- it's all the same H hydrogen), in exchange for a dissolved calcium or magnesium ion. Those big polyphenols have many many ion-exchange sites. Those H+ cations that are released into the water don't get adsorbed to carbon, I.e. carbon doesn't "reduce acidity."

So when polyphenols are "pulled" from the water and adsorbed to carbon surfaces, that makes the water less yellowish.

But H+ remain in the water, which is consequently more acid.

So, you want the softening and the acids, but still, you don't want the yellow. Here's what I don't know: Do you have to put in your peat or tea bag or Osmunda fiber first, let it work all it's going to, then when the ion-exchange sites are all loaded up with as much Ca and Mg as they're going to get, then do you put carbon in the filter to remove the yellow polyphenols?

Or, can you do it all at the same time, because the polyphenols stuck to the carbon are still able to do the ion-exchange thing from their adsorbed position?

THAT's what I don't know...

I spell this out so you can see my mistakes, if I'm misunderstanding this stuff... if what I "know" is wrong..

'cause I'm no chemist!
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Tommy
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Joined: 06 Feb 2003
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PostPosted: 2003.09.04(Thu)21:08    Post subject: Reply with quote

wetmanNY wrote:
'cause I'm no chemist!


Could have fooled me Wink
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number6
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Joined: 07 Feb 2003
Location: Ontario, Canada

PostPosted: 2003.09.05(Fri)16:05    Post subject: Reply with quote

Some test results:

One, cheap charcoal contains ash, expect to see a disaster (skyrocket!) with your pH...

two, tanins are removed and there is a slower effect on pH with good activated charcoal present.

Around the same time as the volume of peat starts to recolour the water the pH will drop at the same rate as the bucket with no carbon.

Conclusion: the polyphenols absorbed do not continue to act on the pH measure in the tank...

Tried it ala five buckets in the garage....
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wetmanNY
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Joined: 24 Aug 2003
Location: NY NY

PostPosted: 2003.09.05(Fri)23:13    Post subject: Reply with quote

Aha! so then, the advice "don't rush it" continues to hold good whenever you're realing with fishtanks...
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