Re: [APD] Hair algae

[Vaughn Hopkins <hoppycalif at yahoo_com>]

Tom,
As long as you are using the AP Pharmaceuticals reagent, or any other  
reagent using bromothymol blue as the indicator the results will be  
the same.  And, if you set the KH of the distilled water in the bulb  
at 4.0 +/- .2, it will be green at 30 ppm of CO2 in the water.  The  
error range is only about 25 to 40, due to inability to judge what  
green is, but that isn't at all hard to do -  green isn't a color  
that is hard to judge, as long as your vision is about average.  So,  
the "green level" will be whatever you want it to be green at - 30,  
40, 45 ppm (Kh=4, 5, 6).  If you want it to be green at 20 ppm, use  
KH=2.5 degrees.  This isn't even sensitive to  how much indicator  
reagent you put into the bulb water.  You can use the standard 3  
drops per 5 ml of water that AP says to use, or go to 12 drops, and  
all that changes is the intensity of the color, not the actual color.

And you guys thought sliced bread was great?

Vaughn H.

On Oct 16, 2006, at 8:53 AM, Thomas Barr wrote:

> The drop checker Vaughn mentions is a wise idea. It's not
> particular narrow in accuracy, but it's more accurate in many
> cases and gets around any non bicarbonate buffer issues.
>
> I'm not sure the optimal range of the solution (turns green) is
> set at 30-35ppm though..............it might be set at 15ppm or
> 20ppm etc.
>
> Different brands are set at different levels, who knows........

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