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Re: Aquatic Plants Digest V3 #646
In a message dated 11/15/98 10:20:07 PM Mountain Standard Time,
yurko at warwick_net writes:
> There *must* be another reason than
> "gassing off" why the pH rose. Was there any cigarette (or other) smoke
> (amines)?
No one here smokes
> Did anybody wash the floor in the house (ammonia)?
Spic and Span. I have never noticed any ammonia smell from that. I'm single,
and not a particularly good housekeeper.
> Other trace
> sources of alkalies? And I mean *traces* -- it does not take much at
> those concentrations. Some alkaline substance in the air would account
> for the observation that covering the tank slowed down the acidity loss.
Then is anyone's fish safe? Just scrubbing the kitchen should take all of my
S. American tanks out of tolerance. The same pH rise was not observed when
using sulphuric acid in the same house, exposed to the same chemical agents at
the same intervals and concentrations. Domestic contaminants is an unlikely
consideration.
> You don't mention the original hardness, alkalinity and pH of the water,
GH 60 ppm, alkalinity 80ppm. I originally questioned these values, but the
local water works confirmed them to be consistent with their tests, and
several folks on the Apisto list confirmed that this is possible, and even
common. The pH started at 7.8
> how much acid you added, as well as the final values, except final
> alkalinity of 40 ppm. What was the final pH and how much it rose?
The exact details escape me. I added something like one TBSP per gallon of 2%
HCL to get a short term drop from pH 7.8 to 6.5. The next day, alkalinity was
down to 60ppm and pH was back up to 7.6. I repeated the dose and the next day
it was an alkalinity of 40ppm and pH 7.4. After that, there was no long term
change (overnight), although I could get a drop of about 1.0 in pH in the
first few minutes after dosing.
>What type/brand of pH meter did you use? any other experimental details --
> what indicator is used in your alkalinity kit, etc.?
I am not sophisticated enough to spend big money on eloctronic gadgets. I
used the Wardley alkalinity kit which requires adding titrant to a vial. By
increasing the volume of the test sample, I can adjust the accuracy down to a
pretty tight scale, like 5ppm. I have a number of pH kits floating around. I
used primarily the Tetra and Aq. Pharmaceuticals tests. The alkalinity test
was purchased new at the time the test began, and my pH test kits don't ever
get old enough for the reagents to exceed their functional shelf lifes.
Dave Gomberg confirmed from his own experience that 40ppm was as low as he
would expect the alkalinity to drop using HCl.
With Sulphuric acid, I got steady reductions in alkalinity until it was gone.
Then I could reduce pH to 6.5, or for some of the fish, even 5.5 with no
problem. The first suphuric acid test was run in the same tank after I washed
it thouroughly (okay, so I just rinsed it a bunch, no cleansers or chemicals)
and set it back on the same stand, in the same room, exposed to the same
routine "household vapors".
I don't know what else I can offer to say, George, except maybe you can run
some tests of your own, and maybe find that "other explanation". I'm sold on
Dry acid from the swimming pool store. Yes, I know it is a modifoed form of
suphuric acid. Don't ask this layman to tell you what else is in there. I
only know for sure that it gives the results I want and muriatic acid doesn't
Also worthy of note: I was using up the 2% solution to reduce buffering in a
bucket of water shortly after I finished my test. I overtightened the cap and
cracked it. About a week later I noticed this crack, and tested the solution
to see if it was still good. Guess what? pH had risen from 1.7 to 6.8. My
explanation as to why? Yep, gassing off. I keep these chemicals on a high
shelf in the garage where they are safe from the rugrats. As my garage is too
busy storing things to house my car, the door only gets opened when retrieving
bikes and lawnmowers and such. No fumes from the car. Either it gassed off,
or the air in this fairly small Rocky Mountain town is more polluted than John
Denver would have us to believe.
Bob Dixon
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