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Re: Peat & Ph
Just to clear things up a little, I'm doing the peat filtering in a 30g
trashcan. The idea is to mix this peat filtered water with tap water to
achieve the desired pH before CO2 injection, manual system.
> How hard (carbonate hardness) is the water? If it is KH 3.8,
>as implied below, this implies that it has a _very_ low CO2 content when
>it comes from the tap, somewhere around 0.07 ppm. This will _increase_
>when the water is exposed to the air, to about 0.5 ppm, from which I would
>expect a pH of about 8.5. A CO2 content of about 1.1 ppm would give
>you the pH you do get, 8.1.
>
The GH of my tap water is 130 ppm and the KH is 66 ppm.
> If you use peat filtering, you will be replacing the carbonate
>buffering with organic acid buffering. The pH you get will depend on
>how much of what acids and how much in the way of metal ions are in the
>solution. Provided there are reasonable amounts of them in there, the
>pH should be pretty stable, and since the peat filtering replaces HCO3-
>with the organic acid anions, you should have enough.
>
Which type of buffering would be the best? Would there be any ill effects on
either the plants or fish by using the peat water with arganic acid
buffereing as opposed to carbonate buffering.
> You have gone from a solution with Ca++ and HCO3- with CO2 (H2CO3)
>to one with Ca++ and (organic acid anion)- with (organic acid). This
>will be brown. The peat filtering you did destroyed HCO3-, creating CO2,
>which left the solution overnight. That is why the pH rose again.
>
I started this experiment over again with freshwater. I filled the 30g
trashcan, then filtered the water for about 4 hours which brought the pH
down to 5.0. After sitting overnight the pH was 5.95.
Is is possible that after the humic acids were depleted from the peat that
the acids equalized with the peat in the filter?
> The result will depend on the contents of the two solutions,
>specifically what buffering agents are in them. If you used pure water
>with a pH of 7.0 and a good buffer solution with pH 8.0, when you mixed
>them you would get pH 8.0.
>
I mixed equal parts of the tap water which has been sitting for a week and
had a pH of 8.4 with the peat filtered water with a pH of 5.9. The resulting
solution had a pH of 7.0
>> Once I get the pH down to where I would like it to be which is around 6.8 if
>> I add carbonate buffers back into the water will the pH go back up?
>>
> Yes, if you don't add CO2.
What I would like to do is get the pH to around 7.0 then add CO2 to bring it
down to 6.8. My thought here is that if the CO2 runs out or malfunctions for
some reason then the pH swing will not be as bad as it is now. Currently
without CO2 the pH in the tank is 7.6
Allen
STLMO