re: Alkalinity-CO2-Test Kits

Daniel Marsh said:
> > We have set up several planted tanks w\CO2 and TWP DI water
> > (reconstituted with their Electro-Right 
Paul Sears said: 
>         Do you have any idea what is in this?  Adding unknown
> things to the aquarium water can be expected to cause problems 
> with getting meaningful measurements.
According to the bottle "Electro-Right adds the right balance of
electrolytes and trace elements including potassium, magnesium,
chloride, sodium, calcium, sulfate, iron, vanadium, titanium, strontium,
and manganese" no percentages or quantities. I was under the impression
that you had to start with something like this to be able to measure
anything. Please feel free to correct my misinformation and advise a
better product or way to start from DI water.

> Phenolphthalein endpoint.  It should _start_ to be visible at
> somewhere a bit above pH 8.3, but as you say, it is _very_ pale in
> that range.

We were hoping for an _accurate_ CO2 test, if this is the best we can
hope for then where do we read it? The test instructions say to add
drops until it becomes a light pink, we are using the lowest range
available (23ml water, 1 drop phenolphthalein) so each drop of acid
equals 1.25 mg\l CO2. There is quite a range of drops 6? when