# Purigens effect on humic acid and anti fungal benefits



## Alastair (4 Jun 2013)

Just out of curiosity, even though my tank water is pretty clear particle wise, im thinking of trying purigen again but on a low tech tank. 
I know the stuff absorbs organic compounds tannins etc, so if this is the case does it mean that it would also remove all the beneficial properties that come with alder cones almond leaves and peat etc ie antifungal and ph lowering plus any humic acid produced??? 

I only ask as I have a fair amount of alder cones and almond leaves. I dont mind the tannins etc but do have some fine particles that the filtet doesn't quite catch which purigen would hold onto but I dont want to lose what benefits I get from the cones and leaves. 

Thanks for any help

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## sciencefiction (5 Jun 2013)

That's an interesting question.
I asked similar stuff a while ago and I removed mine from two of my tanks because of what Darrel said on that thread. Here it is:

Is Purigen safe? | Page 5 | UK Aquatic Plant Society


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## roadmaster (5 Jun 2013)

Been using Purigen in low tech 300 litre tank for around eight month's so far, and have seen no negative effect on plant's ,fishes.
If I were Relying solely on organic waste for plant food I might not see the sense of using it,but I add inorganic fertz(,mineral salt's)each week, so plant's still appear to thrive for me.
Bring's me the clarity I desire despite several large pieces of driftwood I have with anubia attached.


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## dw1305 (5 Jun 2013)

Hi all,


Alastair said:


> I only ask as I have a fair amount of alder cones and almond leaves. I dont mind the tannins etc but do have some fine particles that the filtet doesn't quite catch which purigen would hold onto but I dont want to lose what benefits I get from the cones and leaves.


I think that Purigen will remove the DOC compounds you want. I don't like floss, but a fine sponge (PPI30) might do?


roadmaster said:


> If I were Relying solely on organic waste for plant food I might not see the sense of using it,but I add inorganic fertz(,mineral salt's)each week, so plant's still appear to thrive for me.


It isn't really nutrients that are an issue, it is the humic acids and tannins (natural organic matter (NOM)) that the Purigen removes.  Black water fish have evolved in water rich in both dead leaves and humic substances.

Personally I have no doubt that care for these fish is less problematic in tanks with humic compounds present.

Have a look a this article by Colin Dunlop <  All the leaves are brown… — Seriously Fish> & this one from the "Skeptical Aquarist" <Humic substances | The Skeptical Aquarist>.

This is from "Influence of Natural Organic Matter Source on Copper Speciation As Demonstrated by Cu Binding to Fish Gills"


> Rainbow trout (_Oncorhynchus mykiss_, 2 g) were exposed to 0−5 μM total copper in ion-poor water for 3 h in the presence or absence of 10 mg C/L of qualitatively different natural organic matter (NOM) ...... The presence of NOM decreased Cu uptake by trout gills as well as Cu concentrations..... Furthermore, the source of NOM influenced Cu binding by trout gills with high-color, allochthonous NOM (ie. tannins from the leaf litter of terrestrial trees) decreasing Cu accumulation by the gills more than low-color autochthonous NOM


cheers Darrel


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## Andy Thurston (5 Jun 2013)

If waters pretty clear floss is ok. I change mine when i clean filter every month. Fine sponges clog in about the same amount of time as floss and im too lazy to rinse so floss is cheaper to replace


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## sciencefiction (5 Jun 2013)

I use sponges and I think the result is way better than floss. I'll never use floss again, it was counterproductive. I haven't had an issue with them clogging either, maybe it depends what sponges you are using.


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## Alastair (5 Jun 2013)

dw1305 said:


> Hi all,
> 
> I think that Purigen will remove the DOC compounds you want. I don't like floss, but a fine sponge (PPI30) might do?
> 
> ...




Thanks for that informative post as always darrel thanks.  I was hoping you chip in and the link science fiction posted too helped so ill not be using purigen.  I prefer the tanning look anyway.  

I know its a slightly off topic subject darrel but what effect would the low ph and humic substances etc have on any added fertilisers.  Would they effect dissolution of iron copper etc or would that only happen in extremely low ph???

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## dw1305 (5 Jun 2013)

Hi all,


Alastair said:


> I know its a slightly off topic subject darrel but what effect would the low ph and humic substances etc have on any added fertilisers. Would they effect dissolution of iron copper etc or would that only happen in extremely low ph???


I think once you get below pH7 a lot ions will become more available, if you have a lot of DOC most of those ions will be complexed, and what happens after that is going to depend upon a number of factors.

I think this is about right <Chelation | The Skeptical Aquarist>, and it is the approach we used, but it isn't a subject where I know much about the actual chemistry (I'm not a chemist).

cheers Darrel


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## Alastair (5 Jun 2013)

dw1305 said:


> Hi all,
> 
> I think once you get below pH7 a lot ions will become more available, if you have a lot of DOC most of those ions will be complexed, and what happens after that is going to depend upon a number of factors.
> 
> ...



Thanks Darrel. I read your last link and just tried to get my head around some of its explanations. So to my understanding it still allows some iron etc to be taken up by plants but mentions humic acid can bind potassium calcium and magnesium thus taking it out of circulation so I take it this means that any added to benefit plants or minerals for shrimp are not going to be used up??? 

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## dw1305 (6 Jun 2013)

Hi all,


Alastair said:


> So to my understanding it still allows some iron etc to be taken up by plants but mentions humic acid can bind potassium calcium and magnesium thus taking it out of circulation so I take it this means that any added to benefit plants or minerals for shrimp are not going to be used up???


There isn't really a black and white answer to this, you can think of it like velcro, the ions are held, but not permanently stuck. Which ions are held and released depends upon the chelator, their relative abundance and the lyotropic series <Lyotropicseries>.

A basic rule would be that monovalent ions like NO3- and Na+ are exchanged for all other ions with a higher valency SO4--, Ca++, Mg++ in the water column.
For anions you have: (most tightly held) SO4-- < F− < Cl− < Br− < NO3− < I− (least tightly held).

If you have a high enough concentration of any ion it will displace other ions, even if they are higher up the lyotropic series.

Have a look at this PDF (from lenntech), in this case you just have to substitute DOM when it says "ion exchange resin" <_http://www.lenntech.com/Data-sheets/*Ion*-*Exchange*-for-Dummies-RH.pdf_>

cheers Darrel


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## Yo-han (6 Jun 2013)

This are the kind of discussions why I joined this forum, thanks!


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## dw1305 (6 Jun 2013)

Hi all


Yo-han said:


> This are the kind of discussions why I joined this forum, thanks!


 I'm pleased you've enjoyed it, although anecdotally it is the kind of discussion which puts a lot of people off.
I'm probably strange, but I really like to know "why" something does, or doesn't, work.

cheers Darrel


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## Yo-han (6 Jun 2013)

Me too! Not just throw a daily Excel overdose in your tank and your problems are gone, so these kind of info is much appreciated!


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## Alastair (6 Jun 2013)

dw1305 said:


> Hi all
> I'm pleased you've enjoyed it, although anecdotally it is the kind of discussion which puts a lot of people off.
> I'm probably strange, but I really like to know "why" something does, or doesn't, work.
> 
> cheers Darrel



Doesnt put me off darrel I think its really valuable to myself and many....after reading through it a couple of times though


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