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Re: HCl problems

> From: IDMiamiBob at aol_com
> Subject: Re: Aquatic Plants Digest V3 #646
> 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.

	I think it is pretty definite that what you were adding wasn't
2% HCl.  The first short term pH drop implies that it was about a factor
of 10 more dilute than that, and the first alkalinity drop that it was
a factor of about 4 more dilute.  These numbers are pretty rough, but
are based on the "1 TBSP per (U.S.) gallon" above.  The later failures
to get a pH drop indicate an even more dilute acid solution, as does
the high pH (1.7 for the solution).  Where did this stuff come from?

	One possibility that occurs to me is that the "HCl" solution
may also have a buffer in it.  That would wreck the alkalinity measurements
and make it impossible to get the pH down.

> 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.  

	I'll spell "repetitive" properly this time!
Paul Sears        Ottawa, Canada