Re: PH crashing up?

[Larry Jones <ljones at usc_edu>]

On 4/26/03 5:23 AM, "Aquatic Plants Digest"
<Aquatic-Plants-Owner at actwin_com> wrote:

> Subject: PH crashing up?
> 
> The water I am using is a mixture of RO water, and tap water.  I add a little
> baking soda, Kent's RO right, and some Kent's PH control Minus.  After mixing
> for about 24 hours, my change out water has a Ph of around 6.5, A GH of 2, and
> KH of 2.
> 
> What is happening is this:  I add my mixed water, and the PH drops down to
> around 7.  Within 24 hours it will rise up to around 8.4!  I tested the KH,
> and it is still at 2 or less in some cases.  So what is driving the PH up?
> 
Seems like the 24h mixing raises the c02 in your water and lowers the pH a
little. Then when you add the water to your tanks the plants use the C02 and
the pH goes up. To test this just add the water as before but just keep the
tanks totally dark. The pH should stay the same or maybe drop a little. Also
the fact you say the KH is sometimes lower shows the some of your plants may
be using the bicarbonate from the baking soda as a source of carbon once the
C02 runs out.  That process can really drive the pH high.


Larry Jones
ljones at usc_edu