Does it work? ADA glass dropcheck co2 indicator - Page 2 - General Aquarium Plants Discussions

Bert H · 09-28-2006, 05:07 AM

I understand what Hoppy's saying. Basically, it can be quite difficult to match a particular shade of a color to a color chart when you're holding a test tube in one hand and the chart in another. Now imagine that tube being inside a tank full of water, etc.

Secondly, the accuracy of that particular test (the kh/pH relationship) has been shown to be quite variable depending on the presence of any other acids in your tank. Many folks have thought they had much higher or lower amounts of CO2 than what was in actuality due to these errors.

Thirdly, the method is accurate in the sense that it is based on a simple acid/base colorimetry reaction where a pH indicator will change colors depending on the pH present.

Clear as mud now?

Personally, I prefer the degassed tank water measurement followed by increasing the gas and observing your fish.

Gomer · 09-28-2006, 08:56 AM

Quote:

Secondly, the accuracy of that particular test (the kh/pH relationship) has been shown to be quite variable depending on the presence of any other acids in your tank. Many folks have thought they had much higher or lower amounts of CO2 than what was in actuality due to these errors.

This doesn't matter one bit. The indicator is disolved in DI/RO/Nanopure water. The GH and KH is zero. Since the color change is purely a gas phase equilibrium, what you see is what you get. Bromothymol blue is blue at pH 7.6 and yellow at pH 6.

Bert H · 09-28-2006, 09:13 AM

Quote:

This doesn't matter one bit. The indicator is disolved in DI/RO/Nanopure water. The GH and KH is zero. Since the color change is purely a gas phase equilibrium, what you see is what you get.

I didn't realize that Tony. Thanks for clearing it up.

newguy · 09-28-2006, 10:16 AM

from adg, looks pretty easy to tell

hoppycalif · 09-28-2006, 03:29 PM

Quote:

Originally Posted by Gomer

This doesn't matter one bit. The indicator is disolved in DI/RO/Nanopure water. The GH and KH is zero. Since the color change is purely a gas phase equilibrium, what you see is what you get. Bromothymol blue is blue at pH 7.6 and yellow at pH 6.

So, this test takes the tank water out of the equation? Does this mean it assumes that the CO2 in the tank water and in the indicator device is the same in ppm, by having the CO2 being measured come from the tank water? I'm not a chemist, so I don't know much about this - does this truly remove the variables in our tank water from the picture? If so, I will certainly buy one of these. My eyes work pretty well for judging yellow-green-blue, so it would work pretty well for me.

Now, what ppm of CO2 does ADG consider to be ideal? And, is the color change sensitive enough to judge "ideal" + 10 ppm as bein different from "ideal" minus 10 ppm? Since these seem to still be out of stock we have time to explore these questions before sinking the $38 + shipping in one.

Steven_Chong · 09-28-2006, 08:55 PM

I bought one these things this summer.

And here's my reasoning:

-I'm in Japan, and it's here in front of me for $20.
-It's sexy

There you go.

lol (I'm an idiot, yeah??)

Anyway, it's as the pictures show. I run an air stone at night, so the indicator's usually a dark green in the morning, and at the "just right" yellow color by the time I come back from class. I'm not so good with sophisticated tests so this is a good tool for my level of intelligence I think.

Is it necessary? Not at all. XD

Is it sexy? Yes!! <33

Anyway, I have one, it's useful, and I seem to be getting the CO2 my plants need to them. That's all.

hoppycalif · 09-29-2006, 09:25 AM

This has aroused a lot of interest for me. The idea that the indicator/water solution would not be tank water was very intriguing since that would seem to get around the acidity/alkalinity variations in tank water that are not associated with CO2. So, I emailed Jeff Senske at ADG. I asked:

Quote:

I am very interested in this method for measuring how much CO2 is in
my aquarium. So, I have a few questions:
1. On APC this was discussed and it was said that this uses pure
water, with no KH, plus the reagent in the bulb, leading me to
believe that the CO2 indication is independent of the contaminants of
various kinds in the aquarium water. This would eliminate the effect
of alkaline substances or acid substances in the water. Is this true?
2. Does the color chart with the unit tell you the pH or the ppm of
CO2? The information on the website leads me to believe that all it
does is indicate "acceptable" if the solution color is greenish. If
so, what ppm of CO2 does that indicate and with what accuracy?
3. How often do you have to replace the indicator solution?
4. When will they be back in stock?
Thanks in advance for any information you can provide on this very
intriguing new device.

As I expected, I got a quick, informative answer back this morning:

Quote:

1. Actually you fill it with aquarium water.

2. It tells you pH. There's no ppm indicated and the "accuracy" is more in
terms of telling you that you should add more or use less CO2. It's based on
a simple idea of acidity vs. alkalinity and the need for slightly more or
slightly less CO2.

3. I will have to check to see how often the reagent is replaced. I have
never personally used it for more than an initial test to confirm the CO2
supply in a newly set-up tank. It is not something I use routinely.

4. ADA is currently out of stock on the Drop Checker. I tried to order a few
last week. I do not know for sure when they will have more. Likely in the
month or so.

You're welcome. It's not really a new device, though. These types of
checkers and this one from ADA in particular have been around for many
years.

So, for me it is back to the drawing board. This is just a very elegant form of the in-tank pH testers that are available from other manufacturers at much less cost, but also much less esthetic appeal. But, no more dependable.

newguy · 09-29-2006, 02:36 PM

Quote:

1. Actually you fill it with aquarium water.

thanks for confirming hoppy.

werner · 09-29-2006, 07:13 PM

There are knock-offs of this available on eBay here

hoppycalif · 09-29-2006, 09:23 PM

Now that price is low enough to give this serious consideration, but no color standard card is included. The only way I see to use this is to independently determine that you have adequate CO2, and try to keep whatever color that gave as the right color. It does look pretty good though.