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Re: pH, KH, CO2

> From: Harneloot at aol_com
> Subject: Re: pH, KH, CO2
> my KH reads at 2degrees, and my pH at 6.8, which gives me a CO2 of around 8.5 
> by my readings of the chart. thats with my carbo-plus running almost at full 
> strength for two weeks, and with only half the tank planted. (water surface 
> pretty still) 
> if i bump up my KH (by adding sodium bicarbonate?) then my CO2 levels will 
> rise? could i have been getting an "artificial" pH reading because i was 
> using chemi-pure in my filter media? (it is suppose to auto adjust pH, yes?)

	Once again, putting unknown things in makes it impossible to know
what is going on!  I think that "chemi-pure" is some sort of ion exchange
medium.  Which ions it removes and what it substitutes for them depends
on what sort of resin it is, and what was used to regenerate it (if it
can be regenerated).  Whatever the uncertainties, you _know_ that if
it "auto-adjusts" the pH, your measured KH is meaningless, and that you
have no idea what the CO2 concentration is.

	If carbo-plus device generates CO2 by the reaction:

	Ca++  +  2HCO3-  ->   CaCO3(solid)  +  CO2  + H20

you must have Ca++ and HCO3- ions in there for it to work.  This means
that NaHCO3 (sodium bicarbonate) will not do the job, you need to dissolve
CaCO3 in the water (to get Ca++ and HCO3- ions).  You also need CO2 to do
that, so you will have to dissolve it in a container other than the tank, because
the CO2 in there is generated from Ca++ and HCO3- ions, i.e., the CO2 has
to be put into the process somewhere!  The chemi-pure probably removed either
or both of the Ca++ and HCO3- from the water, by the way.

> i just want my plants to flourish!!

	Throw out the chemi-pure, and you might get somewhere.  What is your
water like from the tap?

Paul Sears        Ottawa, Canada