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[APD] RE: high pH/low KH

> From: "Poe Ratana" <poe835 at hotmail_com>
> Subject: [APD] high pH low Kh?
> To: Aquatic-Plants at actwin_com
> Hi,
> I'm in quite an unusual situation here and would appreciate any help.  My 
> aquarium water has a kh of 1, but the pH is 7.2 (GH =3).
> 1) Any clue why this is so?

Sounds about right.
Why would you suspect it should lower?
DI water is close to 7.0
Add some CO2 from the air to a KH=1 and you'll get about 7.2.
Some measurement error might account a little for the off readings.
Add peat(Humic and Fulvic acids) and the pH will drop quite a bit, which is
why you have a pH of 4.7 in Lake Annie and a KH of 1 or so.
But over in another lake with less organic matter and plants a KH of 3 but
a pH in the afternoon of  9.
Some lakes with high plant biomass go from pH 6-9 every day.

> 2) How do I increase kh in my aquarium without further increasing my pH? 
> don't have CO2 injection and don't have access to any DIY equipments, so
> can't really bubble co2 to get the pH down.  How about adding acids to
> bicarbonate solution?

I would steer you clear from that. Peat is about the only thing that would
work well, but why are you SO CONCERNED with pH?
In planted tanks, it'll vary every day, just like in relevant lakes/ponds
with plants in nature.

If you used say HCL or H2SO4 and removed all the KH, what would happen to
the pH then?
Look up the definition of alkalinity. 

Adding CO2 stabilizes things.
If you want to control pH due the removal of CO2, you simply add CO2.

Since you precluded yourself from adding CO2, (You live where there is no
Sugar, water and yeast? Do people make bread there?) you will need to do a
non CO2 method so don't worry about pH. It's going to move around unless
you use all floating plants.

> 3) If I don't have CO2 injection, would having a higher kh have other 
> benefits other than reducing the pH swings?  Would more CO2 from fish and 
> the atmosphere be able to dissolve more and therefore increase plant

No, water with a KH of 2 and KH of 20 have the same amount of CO2 in
solution at equilibrium(the same amount of CO2 is in the air and will
equilibrate with both waters), the pH's are different but the CO2 content
is the same, just like it is in the air.
The KH 2 water would have a pH of 7.2 and a CO2 levels of 3.7 ppm or so,
the hard water would a pH of about 8.2 or so and a CO2 levels of 3.7ppm or

Your pH is slightly lower perhaps because you measured the pH at night or
the Test for your pH/Kh is slightly off, doesn't take much. Give yourself a
little room for error. 
Some plants will use the KH to get at the carbon there and deplete the
water of KH so having some KH in the water is a good idea.
Algae predomiately use KH for their source of carbon(some will do well with
CO2 though), while plants greatly prefer CO2. 
CO2, not soft water and some low pH, is what the plants want to grow well.

The best aquatic plant growth occurs in hard clear water springs rich in
You can come see this for yourself if you'd like.

Plant fest 2004 this June will spend two days at a couple of these
Tom Barr

> thank you very much!

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