# DIY Drop Checker For Under $1



## deondrec (Sep 30, 2008)

great diy. I dont have a Axe Man store in arizona. You should make more and ship them. If the price was right i would buy at least 2.


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## Darkblade48 (Jan 4, 2008)

Very similar to a build I　made a few years back.


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## tjbuege (Jun 23, 2009)

To deondrec: Thanks. I was considering making addition ones and placing several in my tanks, in various spots, to get an indication of CO2 concentrations and dispersion throughout the tank. With regards to building these for others, I wish I could say yes, but I'm not sure I have the time for that. Besides, I'm not convinced the design is optimal just yet. I bet you could find similar parts at any surplus or dollar store. Even if you had to drill your own hole in the cap and use silicon adhesive to fix a plastic tube in place, it would still be a simple project, and not cost much at all. Oh, and the nature of the Axe Man store is, their product can turn over quickly, depending on what it is. There's no guarantee the parts will be there for long. Some items will be here today, and gone tomorrow. Other items, like that Iron Lung (!) have been there for the 30+ years I've been visiting the store!  (I guess there just isn't a demand for antiquated medical equipment...)

To Darkblade48: how did yours perform? I'm trying to figure out what I can change to make the solution react more quickly. I have about 7-8ml of indicator solution in these. I bet if I had less solution, and a smaller air pocket, and a larger area for gas exchange between tank water and air pocket, this might react faster. Your thoughts?

Tim


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## CAM6467 (Feb 11, 2009)

I understand the process of creating KH standard, but what did you use for the PH/CO2 indicator solution (i.e. the portion of the mix that changes color)?


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## tjbuege (Jun 23, 2009)

I simply used my pH test solution from Aquarium Pharmaceuticals. Turns my 4KH solution to a very rich blue color, indicating a pH of about 7.2. For testing pH, the instructions say to put 3 drops in 5ml of tank water. Since I have closer to 8ml of 4KH water in the drop checker, I added about 6 drops to make the color saturated enough to read, but not too much to turn it murky. In one of my tanks, I've managed to get it to a light yellow-green. I'm still experimenting with optimum CO2 dispersion in my other tank. But in both tanks, my plants begin to pearl quite a bit, so I believe the drop checker is working, and that I am approaching 30ppm CO2. But is just takes to long to change colors. Much longer than the average 2 hours or so that most people say.


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## Darkblade48 (Jan 4, 2008)

tjbuege said:


> I'm trying to figure out what I can change to make the solution react more quickly. I have about 7-8ml of indicator solution in these. I bet if I had less solution, and a smaller air pocket, and a larger area for gas exchange between tank water and air pocket, this might react faster.


I think the most important thing is the surface area available between the liquid/air interface. If you were to use a larger test tube, for example, it would likely decrease the time it took for the colour to change.



CAM6467 said:


> I understand the process of creating KH standard, but what did you use for the PH/CO2 indicator solution (i.e. the portion of the mix that changes color)?


You can use any pH indicator that is based on bromothymol blue (or you can just use bromothymol blue itself).



tjbuege said:


> For testing pH, the instructions say to put 3 drops in 5ml of tank water. Since I have closer to 8ml of 4KH water in the drop checker, I added about 6 drops to make the color saturated enough to read, but not too much to turn it murky.


I usually put 6-7 drops into 5 mL of the 4 dkH reference solution. The addition of more drops of the bromothymol blue indicator has no effect on the time it takes for the drop checker to change colours. As long as the solution remains translucent and is not opaque, you are fine.


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## Hoppy (Dec 24, 2005)

For the fastest reaction time you need the area of the tank water to the air surface to be as large as it can be, with the length of the air path to the indicator water to be as short as it can be, with the area of the indicator water to air surface being as large as it can be, with the volume of the indicator water to be as small as it can be. The limit on reducing the volume of the indicator water is the difficulty in seeing the color if it is too small. Someone with lots of spare time, a good understanding of the science involved with this, and computer skills, could probably write a program to optimize all of the dimensions. That isn't me, on several counts.


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## tjbuege (Jun 23, 2009)

Thanks, Hoppy. This is along the lines of what I was thinking. So if I were to get a larger diameter test tube or other type of tube, to use as an air passage, it would have the additional side effect of reducing the space to be filled by indicator fluid, thus reducing the volume of indicator needed to be able to read it. And I can make the air tube shorter as well. I'll see what I can find at my local home improvement store.

Tim


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## 4f1hmi (Apr 22, 2009)

Would the KH solution from aquarium pharmaceuticals works as my indicator or I would have to add something else?


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## Craigthor (Sep 9, 2007)

4f1hmi said:


> Would the KH solution from aquarium pharmaceuticals works as my indicator or I would have to add something else?


Nope, you will either need to buy or make a 4 DkH solution. You cna purchase it from Orlando at GLA or make it youself there is a good how to here somewhere I'm sure.

Craig


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## Darkblade48 (Jan 4, 2008)

4f1hmi said:


> Would the KH solution from aquarium pharmaceuticals works as my indicator or I would have to add something else?





Craigthor said:


> Nope, you will either need to buy or make a 4 DkH solution. You cna purchase it from Orlando at GLA or make it youself there is a good how to here somewhere I'm sure.


I believe 4f1hmi was asking whether the kH test kit reagent can be used as the indicator in the drop checker.

In short, the answer is no, you want to use bromothymol blue as the indicator. This is in the API pH (normal range) test kit. Adding the pH indicator reagent to a 4 dkH reference solution will give you a drop checker that will turn green when CO2 levels reach 30 ppm.


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## 4f1hmi (Apr 22, 2009)

Darkblade48 said:


> I believe 4f1hmi was asking whether the kH test kit reagent can be used as the indicator in the drop checker.
> 
> In short, the answer is no, you want to use bromothymol blue as the indicator. This is in the API pH (normal range) test kit. Adding the pH indicator reagent to a 4 dkH reference solution will give you a drop checker that will turn green when CO2 levels reach 30 ppm.


 Thanks you for the info. I actually made the drop checker from this tread but used a plastic air tubing instead of a test tube. My only problem is the solution which turns green when I tried to use the 4dkh from API. I will buy the solution then. :thumbsup:


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## kid creole (Dec 25, 2008)

To speed it up, use less water. The other pieces are going to be negligible, considering your geometry is defined already.


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## Darkblade48 (Jan 4, 2008)

4f1hmi said:


> My only problem is the solution which turns green when I tried to use the 4dkh from API. I will buy the solution then. :thumbsup:


Not too sure what your problem is here; API doesn't make a 4 dkH solution.

Unless you meant to say that your reference solution immediately turns green when you add the API pH indicator (bromothymol blue) to it. If that is the case, either the test reagent is suspect, or the 4 dkH reference solution is not really 4 dkH.


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## 4f1hmi (Apr 22, 2009)

Darkblade48 said:


> Not too sure what your problem is here; API doesn't make a 4 dkH solution.
> 
> Unless you meant to say that your reference solution immediately turns green when you add the API pH indicator (bromothymol blue) to it. If that is the case, either the test reagent is suspect, or the 4 dkH reference solution is not really 4 dkH.


 Thanks for your patience with me Anthony:icon_redf. I am not so familiar with these test kits that is why. I am actually trying to use the KH (carbonate hardness) test solution of API by adding 4 drops of aquarium water to make it 4dkh:eek5:. The moment I put the 4 drops of water. It turns green right away and no changes from there. I do not have that bromothymol blue. So it seems that the solution is not appropriate and will have to buy what you are recommending.


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## Darkblade48 (Jan 4, 2008)

4f1hmi said:


> I am actually trying to use the KH (carbonate hardness) test solution of API by adding 4 drops of aquarium water to make it 4dkh:eek5:. I do not have that bromothymol blue. So it seems that the solution is not appropriate and will have to buy what you are recommending.


Yes, this is incorrect. The kH test kit does not have anything to do with this.

You need a reference solution that will measure 4 dkH. This can either be bought, or made yourself with sodium bicarbonate.

Once you have this reference solution, using the kH test solution, it should measure 4 dkH. 

However, in order to properly use the 4 dkH reference solution in a drop checker, you will need bromothymol blue (the API regular pH test kit is this chemical).


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## 4f1hmi (Apr 22, 2009)

Thanks a lot for your help Anthony! I am in the process of getting the solution.:thumbsup:


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