# [Wet Thumb Forum]-Humic on a filter



## bebop (Jul 8, 2003)

do you guys use this... and also are tanins good for the plants and fish?


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## bebop (Jul 8, 2003)

do you guys use this... and also are tanins good for the plants and fish?


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## Rex Grigg (Jan 22, 2004)

If you mean peat I have used it in the past. If you are trying to breed some wild blackwater fish you have to use it to get them to breed. Normally most of us will avoid using peat as it messes with the pH/kH/CO2 chart.

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## gsmollin (Feb 3, 2003)

Yes, peat messes with the pH/KH/CO2 chart, but it messes with it in a totally predictable manner. If you want to use peat, and you want to add CO2, there is no reason why you can't do both. There are reasons why you need to consider peat carefully in your plans, and depending upon what exactly you are doing with the peat, this may be one place where a pH controller adds value to the setup. Nevertheless, CO2 concentrations can be predicted accurately with or without peat addition to the water.

If you are intent on adding peat and CO2, and want to know how to do it, I can explain.


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## perrush (Feb 24, 2003)

@ gsmollin :

the pH/KH/CO2 relation is totally messed up by the use of peat. why do you think you can still predict the CO2 levels ?

@ bebop :

rather accidental I read today an article which said the tanins can act as chelators. That would explain why plants can benefit from peat filtering.

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## gsmollin (Feb 3, 2003)

> quote:
> 
> Originally posted by perrush:
> @ gsmollin :
> ...


What makes you think that? I don't think I can measure CO2 levels with peat in the water. I KNOW I can measure CO2 levels with peat in the water. I have done it for quite some time. It's very simple. However, every time I post this information, I get no response, so I have become reluctant to bother. I may even have the original work I did on this problem, and posted over at Tom's. If you are really interested, I can get it for you.


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## 2la (Feb 3, 2003)

If you're injecting CO2 at a certain level into a non-peat-filtered tank, wouldn't you have the same CO2 concentration if you just added peat to the filter's media chamber--just at a lower pH? Or am I taking too simple a view of this?

 
(Click for pics)


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## Jon Mulzer (Mar 9, 2003)

I would be interested to see your work gsmollin. Feel free to post.

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15XH, 36W PC, XP-1, Onyx Sand, DIY CO2

Crypts spiralis, ciliata, balansae and wendtii bronze and red, pennywort, wisteria and java fern and moss.


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## perrush (Feb 24, 2003)

@ gsmollin :

would be interesting to know how you calculate your CO2 from KH and pH readings when have peat in the water.

As I see it you add extra buffers with peatfiltering. So thse extra buffers will take up some H+ which comes free when CO2 dissolve and therefore the pH won't show as much change as without the peat.

Problem is that you don't how how much tanins there are in the water and that you don't know at which pH they interfere.

But I'm always open to suggestions ;-)

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## gsmollin (Feb 3, 2003)

> quote:
> 
> Originally posted by 2la:
> If you're injecting CO2 at a certain level into a non-peat-filtered tank, wouldn't you have the same CO2 concentration if you just added peat to the filter's media chamber--just at a lower pH? Or am I taking too simple a view of this?
> ...


Nope. That's all there is to it. Adding peat changes both KH and pH, but it has no effect on CO2. The real understanding, however, is that the relationship between KH, pH, peat, or any other source of hydrogen ions, and CO2 is 
_linear_. What this means is that we can separate their contributions by appropriate experiments. I have done these experiments, and can post the experimental procedures, if anyone is interested in that. For now, I will give you the upshot:

You can measure pH, KH and compute "apparent" CO2 in the water, with the CO2 OFF in your tank. You will get a number. Let's say that number is 15 ppm. You also know that the water contains 3 ppm CO2 equilibrium level. This means that the peat is adding 12 ppm "CO2 equivalent" of acid to the water. Now you start CO2 injection and read pH, KH again. You look at the chart and it says 30 ppm. Subtract the 12 ppm from the 30 ppm, get 18 ppm. That is how much CO2 you have now.

One of the difficult parts here is the starting and stopping of CO2, and gathering of readings. You will need to take a lot of readings to get an understanding of the settling time of your aquarium, and its cyclic variations during the day/night. I spent several days with the CO2 OFF, then days more with it ON. However, this is effort well spent, becasue it allows you to add peat to your water, or like me, to add CO2 to an old aquarium that has reached a point where it is like a black water swamp without any peat.


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## Roger Miller (Jun 19, 2004)

gsmolin,

The equilibrium level of CO2 in water exposed to the atmosphere is not 3 ppm. It's actually less than 1 ppm. The background level of 3-5 ppm that we typically see in aquariums is produced by respiration (including bacterial respiration) in the aquarium.

Aside from that (probably useless) detail, the problem of determining CO2 in the presence of other buffers is one that I've worked on. I think Paul Sears spent some time working on it, and there are one or two methods available on the web. I'm not sure I understand how your method works. Could you spell it out in painful detail?


Roger Miller


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## gsmollin (Feb 3, 2003)

Roger,

That's intriguing, but I did measure 3 ppm in a well aerated water sample that I used in my experiments. No fish were in the sample. Nevertheless, I could have been measuring equilibrium CO2 plus some other source of hydrogen ions in the water, because it was not a distilled water sample. Like you noted, it does not change the results of the experiment, but it could possibly explain the 2 ppm error in the results of the experiment. 

I shall post all the ugly details as soon as I collect them. It's a few years old, and it may be on my home computer, or I may have to try and retrieve it from Tom's Place archives.

I shall be starting a new thread for this in the "Aquarium Maintenance and Science" forum. I notice bebop has dropped out of the exchange; he may be lurking, but it's wrong to hijack his thread.


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## Rex Grigg (Jan 22, 2004)

Don't look at it as a 2 ppm error. Look at it as a 200% error.

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## gsmollin (Feb 3, 2003)

Ok I'm not going to bite on that, so you can just troll away.

There's a number of problems with the old posts. I contacted Tom Griffin about resurrecting the archive containing the posts at Tom's Place, and he has informed me that the aechives are lost







. What a shame, since it was a lively discussion between Robert Ricketts, myself, and a number of others who are now lost too. I do have the major experiment disclosures in Word format on a hard drive- but that hard drive is on a defunct notebook computer







(. There will be a slight delay while I get the lost data off of the hard disk, and until then I remain

gsmollin


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## gsmollin (Feb 3, 2003)

OK Roger Miller, I am posting the long form of the experiment over in "Aquarium Maintenance and Science". It's titled "Titration of a solution of two acids, humic and carbonic (long)".

[This message was edited by gsmollin on Thu August 14 2003 at 07:52 PM.]


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## anonapersona (Mar 11, 2004)

Dumb question time,

why can't we just use the CO2 test from the Red Sea test kit, or some other company taht makes one to measure CO2 directly? My Red Sea kit doesn't appear to use the KH/pH tables at all. "This test measures only the dissolved CO2 relevant to the plants, thus excluding the bicarbonate."

anona, probably missing the point completely and therefore needing clarification


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## gsmollin (Feb 3, 2003)

All of the tests commonly available measure pH in some manner. The Red Sea kit, and the LaMott CO2 kit perform a titration. The LaMotte is just like chemistry lab, where you drop KOH solution into a sample until a phenolpthalein indicator turns pink. None of these kits know the difference between CO2 or battery acid. So if there is some other acid in the aquarium, it will throw the readings off. That's the issue with peat, since it forms humic acid in the water. The extra acid shows up in the CO2 kit as CO2.


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## Rex Grigg (Jan 22, 2004)

> quote:
> 
> Ok I'm not going to bite on that, so you can just troll away.


 I don't look at it as trolling. It's a valid point. If I told you a hamburger was $1 and then charged you $3 would you just figure it was only a couple of bucks?









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## gsmollin (Feb 3, 2003)

This isn't about the price of hamburger. Read the post over on Aquarium Science, and comment on the whole thing. FYI the accuracy of the LaMotte CO2 kit is about 1-2 ppm, and so measuring 1 or 2 ppm can give errors equal to the reading. The accuracy of any measurement system is always specified as percent of full scale, which is 50 ppm for the LaMotte kit. Therefore, the 1-2 ppm error is 2-4% of full scale. If that is significant to your problem, obviously you will need a more sensitive titration setup.


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