Puzzling... high ALK & Ca, low PH

[truebeliever71]

<a href=showthread.php?s=&postid=13643977#post13643977 target=_blank>Originally posted</a> by Billybeau1
Wow. :eek1:

Thanks Anthony. Never seen that one.

I guess I feel like Randy does. I'm not sure how they can accurately measure alkalinity in seawater.

Maybe you can find the API liquid alkalinity kit locally. They are under 10 bucks and quite accurate from my testing.

Billy... I've check and cannot find the liquid one locally. Ooh well. The Seachem one works the same way... liquid drops until the water changes color. It seems to me on cue with the test strips say as well as the LFS. (I forget what they're using.)

 

[Randy Holmes-Farley]

I just found a description of how one of these strips works, and it does not give me much confidence in the method.

It is just an acidic pad with a pH indicating dye that shows what pH is attained with a fixed amount of acid in the strip. Importantly, they claim the strip must be exposed for exactly one second (which makes sense since if you allow unlimited time, all of the acid will leach away to the test solution).

http://www.galladechem.com/catalog/...st-strips-70-425-ppm-em-quant-1-pk-of-100.htm

from it:

Remove 1 analytical test strip and immediately reclose the tube.
Immerse the reaction zone of the test strip in the measurement solution for 1 second.
Shake off excess liquid from the test strip.
After 1 minute compare the color of the reaction zone with the color fields on the label. Determine with which field the color of the reaction zone coincides most exactly and read off the corresponding concentration value. If an exact color match cannot be achieved, estimate an intermediate value.