I found this while searching for a drop checker....


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.


Q: Is this true?

It is neither true nor false. Amano does not use a drop checker, nor does Jeff Senske - I asked him about this before I started my experimenting with the device. So, as far as ADA is concerned, this is just a way to measure pH of the tank water. But, if you use distilled or DI water in the device, instead of tank water, and if you adjust the KH of that distilled water to 4 dKH, the water will be green when the drop checker water is at a pH of 6.6. And a pH of 6.6 with a KH or 4, with nothing in the water to affect acidity or alkalinity except CO2 and carbonates or bicarbonates, means the water has 30 ppm of CO2 in it. The air gap between the water in the device and the tank water makes the ppm of CO2 in both bodies of water be the same. So, the drop checker is measuring the amount of CO2 in the tank.

The only company that recognizes the above, as far as I can tell, is Dennerle, who sells their drop checker with the 4 dKH fluid and pH indicator reagent already in it.

The accuracy of the drop checker is very good compared to every other way of determining how much CO2 is in the water. Consider: you can tell the difference in the color between a green that is slightly yellow (pH=6.5) and a green that is slightly blue (ph=6.7). You can set the KH to 4 +/- about .2 very easily. So the range of values for ppm of CO2 when you think it is green is from about 25 to 40 ppm. Both extremes are acceptable for the plants and the fish.

I have left the fluid in mine for 3 weeks and longer without seeing any problems, other than that the glass slowly builds up biofilm, so it needs cleaning. So, if you did routine solution changes every 2 weeks you should have no problems with it.

thank you for clearing that up. I just ordered a Red Sea brand CO2 indicator because the ADA brand will not be in stock for purchase for a few weeks. Will this one come with the 4 dKH fluid and pH indicator reagent you mention above? You say the only company recognizing this application is Dennerle, does this mean that the Red Sea product is not intended for this?

RlxdN10sity - Read this thread:

Aquarium Advice :: View Topic - How to make a reference KH solution for CO2 measurement

Thanks Dapellegrini, that was a very helpful and informative thread. I like the pics...

We all need to get the information in this thread out to everyone: Making Standard KH solutions When we make a mistake we need to acknowledge it.

Ya, I would have posted my whole process up on this board, probably in that thread, but it wouldn't let me use more than 4 pictures in a post (files that I am hosting)...

I think I got things a bit mixed up there... Just read that thread VaughnH (thought it was something else).... Looks like if you are going to make your own solution, the prior thoughts were inaccurate... Good news is the new measurements are a bit easier. Instead of 4.99g baked Baking Soda, use 6.00g and don't bake it... From what I understand that should be accurate enough for our purposes... Right?

I made up a new batch of "4 dKH" water yesterday, using the 6 gram number and it worked ok, based on my KH test kit agreeing that I had 4 dKH water. So, I think that is the number to use. I found that it is easier to do this by weighing the baking soda and mixing with a liter of distilled water, then diluting that water down to 4 dKH, than it is to try to do it by relying on the KH test kit and adjusting until you reach 4 dKH. I did it by using 6 grams of bicarbonate of soda in one liter of distilled water (200 dKH), mixing 10 ml of that with 90 ml of distilled water to get 100 ml of 20 dKH water, then mixing that with 400 ml of distilled water to get 500 ml of 4 dKH water, which is the size of my bottle. Pretty straight forward. My test kit said I had just a bit less than 4 dKH, but that could be either my error in mixing or an error in the kit. It is close enough for my purposes anyway.

Want a good laugh?

Tried to figure yesterday wether my ref. KH still reads 5 KH after 1,5 months of storing in a bottle - searched for the solution and found the empty bottle amidst the exact same sized bottles to be taken back to the super market.

Must have filled the solution into the coffee machine eventually

And no, the coffee didn't taste too bad at all.
Hell, I've to do the mixing again...



Best regards,
Detlef