# Accuracy of Drop checker



## Homer_Simpson (Apr 2, 2007)

I ordered this drop checker and set it up as per instructions
http://cgi.ebay.ca/Chame-Co2-Drop-C...hZ015QQcategoryZ66794QQtcZphotoQQcmdZViewItem
for my 40 gallon tank. After setting up the tank and regulator and setting to one bubble per second. I noticed that the liquid in the drop checker remained clear. I had the c02 on a timer so c02 was only being injected in the day time and being shut off at night. I assumed that this was related to the problem, so I decided to leave the c02 on 24/7 to see if that would cause the clear liquid to change color.

:jaw: :scared: 
Before you know it(in a matter of hours), the color turned yellow, so I turned off the 
c02 and turned on the aeration as I did not want to risk endangering my fish from excess c02 eventhough they seemed unphased.

How accurate are these drop checkers?? I know that the goal is to get a nice green color(indicating 30 ppm of c02), but the liquid seems to remain clear if the c02 is injected only in the day time and goes to the dangerous excess C02 color of yellow if left on 24/7, so how do I set up my co2 to get a safe level of c02(green color) that will benefit my plants but won't endanger my fish.

Thanks.


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## phanmc (Jun 21, 2004)

Did you mix the indicator fluid, which is bromothymol blue, with water? The moment you mix the solution should have turned blue unless your water is more acidic. For the most accurate reading, you should be mixing the bromothymol blue with water that has a kH of 4, preferably made with distilled or deionized water so you know there isn't any other buffers or acids affecting the reading.

The drop checker will take a few hours to calibrate.


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## Supercoley1 (May 28, 2007)

Not much to add really except that 4dKH water is used to indicate the ideal of 30ppm at green (and of course there are different interpretations of what shade of green)

Their accuracy is not as per an exact measurement but visually you can se that yellow is danger and blue is too low, so it much easier than testing this and that as long as you understand that there can be a 1-2hr delay from the tank's CO2 level going dangerous and the drop checker going yellow.

This shouldn't be a problem as long as immediately you spot yellow you can turn the CO2 and aerate the water.

I tend to leave my CO2 on 24/7 but at the same time have my lily pipe pulling oxygen into the water so that I always have green andalso always have plenty of oxygen. Some people say that Crypts react better to this method due to there being changes in water parameters when shutting CO2 off overnight.

Finally (I know I said not much more to add. lol) You should ALWAYS use DI water to make your 4dKH solution. It is a reference solution and therefore you need to be sure of what it is a reference to when intepreting its results.

Andy


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## Squawkbert (Jan 3, 2007)

Having read the auction's directions for checker use, I have my doubts as to the quality of the solution you made.

I suspect that what you got in the 10mL dropper bottle was just the indicator solution. If it also has carbonate in it, they should have given you very precise diluting instructions so that it would come out 4dKH.

So, what you need to do is either order some 4dKH solution Billionzz used to sell this - he may still http://liquidarthome.net/khstandard, or search the methods out and make your own. Then add a drop or three of the indicator to that.


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## epicfish (Sep 11, 2006)

Blacksunshine might have some solution too.


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## Homer_Simpson (Apr 2, 2007)

O.k. guys thanks for the information. This is what I did.

(1)Get some tap water or distilled water from the grocery store. [I did not use tap water - I used distilled water]
(2)Fill the drop checker bulb about 2/3 full of the water.
(3)Add about 3 drops of pH test reagent, to get a strong blue color, but not so much that the water becomes opaque with the blue dye.
(4)Use the suction cup on the "drop checker" to suspend the device two or three inches below the tank water surface, with the "horn" of the "drop checker" pointing downwards.

I did not realize that there is a 2-3 hour wait for calibration, but this is also puzzling. The c02 was on in the day/off at night, for at least a day, with no change in color in the liquid which was transparent. Then, as soon as I left the c02 on 24/7 boom! within hours the color turned a piss yellow.


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## Homer_Simpson (Apr 2, 2007)

epicfish said:


> Blacksunshine might have some solution too.


I already ordered a couple of drop checkers from BS with solution, so hopefully I retest BS solution with this drop checker when I get the solution.


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## Squawkbert (Jan 3, 2007)

Distilled water + indicator = yellow. You need the carbonate in there to buffer the solution so that the addition of CO2 will turn it green or yellow. DI=no buffering at all, and the indicator is acidic on its own... (usually prepared in a dilute -compared to 4dKH buffer- acid).


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## Homer_Simpson (Apr 2, 2007)

Squawkbert said:


> Distilled water + indicator = yellow. You need the carbonate in there to buffer the solution so that the addition of CO2 will turn it green or yellow. DI=no buffering at all, and the indicator is acidic on its own... (usually prepared in a dilute -compared to 4dKH buffer- acid).


Thanks for the information. While I appreciate your help, please understand that when it comes to this type of thing I am *Homer* Jim Not a *Chemist.* Sorry to say, but that reads like Greek to me. 

Lol,all I want is a plug and play type of solution. I don't want the hassle of trying to determine, measure, and add appropriate amounts of sodium bicarbonate to make the correct solution. All I want to do is: Add appropriate premixed solution into drop checker with distilled water, place it in the tank, and let nature take its course.


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## hoppycalif (Apr 7, 2005)

Homer, go to http://liquidarthome.net/khstandard and buy 4 dKH reference solution. Use it to fill the drop checker bulb just to the mid point of the round ball. Add 2-3 drops of pH reagent, the type that is yellow at pH=6 and blue at pH=7.2. Stick the drop checker in the tank with the horn pointing down. No chemical skills needed, nothing needed but the ability to tell the difference between green, blue and yellow. After about 2 hours the color will be green if the tank water has 30 ppm of CO2 in it (roughly), yellow if it has more and blue if it has less. I'm not a chemist either.


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## Homer_Simpson (Apr 2, 2007)

hoppycalif said:


> Homer, go to http://liquidarthome.net/khstandard and buy 4 dKH reference solution. Use it to fill the drop checker bulb just to the mid point of the round ball. Add 2-3 drops of pH reagent, the type that is yellow at pH=6 and blue at pH=7.2. Stick the drop checker in the tank with the horn pointing down. No chemical skills needed, nothing needed but the ability to tell the difference between green, blue and yellow. After about 2 hours the color will be green if the tank water has 30 ppm of CO2 in it (roughly), yellow if it has more and blue if it has less. I'm not a chemist either.


Thanks Hoppy and thanks to all for responding. What I will do is wait for BS' solution as I believe it is the correct premixed 4dKH solution and by the time I order the on from billionzz as per link you provided, I will probably already receive BS' drop checker and solution, so there would be no point placing another order for a solution at this point.

In the mean time, I will leave the c02 on a timer, so that it shuts off at night and comes on one hour before the lights come on. Hopefully, this combined with weekly water changes should prevent c02 levels in the tank from reaching dangerous levels and hopefully the c02 may be marginal enough to still benefit the plants somewhat. I will also keep dosing Excel, so that should help also. In the meantime, I will test the aquarium PH and KH and use this chart http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm 
to try and get a crude measure of the c02 levels without the drop checker.


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## zQ. (Dec 15, 2006)

I've buy one of that Drop Checker too,but the Fluid is always Yellow,from the start to 1 week later,even when i turn off the CO2


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## Supercoley1 (May 28, 2007)

You need to buy or make a solution with a known KH so that you have this as a reference point.

Then as long as you are using a bromo blue reagent with it it will give you the readings you require.

Not all Ph kits are bromo blue and therefore some will not change at all.

The known 4dKH solution is measuring the change in CO2 as in a Ph change to the water i.e. if 4dKH is 'X' Ph then if 30ppm of CO2 is present in the water once it has passed through the water/air exchange in the drop checker (the entry point where the vacuum is) then the known solution's Ph should change to 'X' -1 which will sendit green.

The CO2 is in effect gradually changing the Ph of the known solution as it enters the solution which means

4dKH+Ph Reagent out of tank is blue (This is the reference Ph)
add 15ppm Co2 to the water and add drop checker (The 15ppm should send the colour between blue and green)
add 30ppm CO2 to the water and add drop checker (The 30ppm should send the colour a nice green
add 45ppm CO2 to the water and add drop checker (The 45ppm should send the colour to a 'piss' yellow)

It is the CO2 changing the Ph within the drop checker that gives you the indication. If you use tank water you are using the kit as a Permanent Ph test rather than a permanent CO2 test.

Andy


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## Homer_Simpson (Apr 2, 2007)

zQ. said:


> I've buy one of that Drop Checker too,but the Fluid is always Yellow,from the start to 1 week later,even when i turn off the CO2


Lol, the drop checker is a good quality one, but I think we both got had as far as the solution goes  Oh well, buyer beware.


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## Supercoley1 (May 28, 2007)

Its not a case of buyer beware. They all come with the same solution and say add to tank water.

The 4dKH is something that others have worked out gives more accuracy.

Mine came with the silly little solution bottle which is basically just bromo blue in itself (some aren't)

Only diff is they say tank water , we say 4dKH (or 2dKH,5dKH) in other words a non altering known reference to compare with.

They're good quality. Mine was from Hong Kong and looks the same as ADA and with the cost of 1 pot of bicarb and 6 litres of DI water (namely about $5 total) you can make the 4dKH (although there are conflicting ideas on how to make it) and jobs a good 'un

An in tank permanent CO2 kit that not only works well but looks good too.

Andy


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## Homer_Simpson (Apr 2, 2007)

Supercoley1 said:


> Its not a case of buyer beware. They *all* come with the same solution and say add to tank water...


This is not totally true. BlackSunshine's drop checker comes with the proper 4dKH solution, with nothing more required at the buyer's end then to place distilled water in the drop checker and add the proper amount of 4 dKH. This is the way it should be with all sellers, considering that it would not cost them an arm and a leg to include the proper solution made with baking soda and distilled water. Why should I have to make my own solution when I paid for *both *the drop checker and the solution.



Supercoley1 said:


> IThe 4dKH is something that others have worked out gives more accuracy.
> 
> Mine came with the silly little solution bottle which is basically just bromo blue in itself (some aren't)
> 
> ...


I agree, the drop checker is high quality. It is the solution that I have a problem with. And as much I hate playing chemist, my impatience has finally driven me to attempt making my own solution. Left C private messaged me this link, and it seems easy enough. Thanks Left C.

Source: http://www.aquaticplantcentral.com/...lants-discussions/37077-how-kh-standards.html

KH standards

Here is the information needed to make a KH standard. When I started using the drop checker method for measuring CO2 there was a lot of confusion as to the proper way to make a KH standard. After a lot of searching and asking questions I found the correct way to make a good KH standard.

I have made the KH standards with the following.

* baking soda (sodium bicarbonate)
* sodium carbonate anhydrous
* a lab certified Alkalinity Standard Solution as NA2CO3 in 10mL Ampules

How accurate you want the standard is up to you. I think the sodium bicarbonate and the sodium carbonate standards are very accurate if they are made right.

If you want a more accurate standard than that you could use the alkalinity standard solution. The reason for the increase in accuracy is because all that needs to be done is the dilution part, the weighing process is removed, which eliminates any errors from moisture in the sample or an inaccurate scale.

To make a KH standard using baking soda you would need the following.

* distilled water
* baking soda (new and unopened would be best)
* .01 gram scale (a calibration weight)
* 500 ml graduated cylinder
* 50 ml graduated cylinder

1. Measure 3000 ml of distilled water using the 500 ml graduated cylinder and put it in a clean container. The container could be an empty 1 gallon distilled water bottle. (I found it easier to use 3000 ml, instead of the often suggested 5000 ml because you can make your standard with 1 gallon of distilled water instead of having to have a larger container or multiple containers)

To read the precise water level in the graduated cylinder.

-Place the cylinder on a flat surface.
-Make sure your eye is on a level plane with the of the meniscus.
-The meniscus is the half-moon curve formed at the surface of liquid.
-Water should be read from the bottom of the meniscus

2. Weigh 3.60 grams of baking soda, add it to the 3000 ml of distilled water and mix well, this will make a 40 dKH / KH standard.

3. Pour 450 ml of distilled water into the 500 ml graduated cylinder.

4. Pour 50 ml of the 40 dKH standard into the 50 ml graduated cylinder

5. Pour the 50 ml of 40 dKH standard into the 500 ml graduated cylinder and mix well, this will give you 500 ml of a 4 dKH standard.

6. If you want a 5 dKH standard instead of a 4 dKH - change step 3 from 450 ml to 400 ml and you will end up with 450 ml of a 5 dKH standard.

A few addition items:

1. Don't heat your baking soda to dry it out or it will change from sodium bicarbonate into sodium carbonate. You could then end up with a mixture of sodium bicarbonate and sodium carbonate, this would change the sample weight needed because it takes less sodium carbonate to make the KH standard than sodium bicarbonate.

2. You can use sodium carbonate anhydrous instead of baking soda. When I found out that heating baking soda turns it to sodium carbonate I thought this might be a good alternative to using baking soda. I bought Lab grade sodium carbonate that is 99.95% pure, thinking it might make a more accurate standard. While in theory it should, I really can't say for sure that it does because when I follow the above instructions both the baking soda and sodium carbonate standards come out correct.

3. Not all of the calculators on the web are correct for calculating how much baking soda or sodium carbonate to use.

If you want to calculate your own weights here is the calculator to use.

'Reef Chemistry Calculator FV'

This calculator is correct, it was off when calculating sodium carbonate but Jose changed it in the last couple of weeks and now it's right.

This calculator rounds everything up because it was made for calculating
aquarium water not small samples. To get precise weights just add some zero's to the sample size.
For example: if you wanted to know how much baking soda to add to 3 liters of water to get a standard that was 40 dkh the calculator would give you a weight of 3.6 grams to add. We want to be accurate to at least .01 grams so instead of putting in 3 liters of water you can put in 300 liters, the calculator will then give you a weight of 360 grams to add which you know would be 3.60 grams.

It has been said that there are a lot of assumptions built into these calculators but that's not correct statement for this calculator when calculating how much sodium bicarbonate or sodium carbonate to use for KH. This calculator will give you the same answer you would get if you calculated long hand, except that it rounds up the numbers (the solution for that is in the above paragraph).

Although there is one assumption in this calculator when using sodium carbonate, it assumes that the sodium carbonate is 100%. You will need to calculate the difference between your sodium carbonate and 100%
For example:
I purchased lab grade sodium carbonate anhydrous and it is 99.95% pure. After I calculate how much to use I have then multiply the answer given by the calculator by .5% and add that to the weight given by the calculator.

4. I have made these KH standards several times with sodium bicarbonate and sodium carbonate. When I follow the instructions listed above the standards has always came out right.

I have also made the KH standards using a lab certified Alkalinity Standard Solution as NA2CO3 in 10mL Ampules. As long as the accurate dilutions are done this should make the most accurate standard. This is what the EPA uses as an alkalinity standard when they are monitoring and assessing water quality.

************************************************** ********

I hope this helps when others when they are making their KH standards and that they won't have to do all of the research I had to do just to get a good KH standard.

Bill


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## Supercoley1 (May 28, 2007)

Homer_Simpson said:


> This is not totally true. BlackSunshine's drop checker comes with the proper 4dKH solution, with nothing more required at the buyer's end then to place distilled water in the drop checker and add the proper amount of 4 dKH. This is the way it should be with all sellers, Bill


If BlackSunshines drop checker came with the proper 4dKH solution then I don't understand why he is adding DI water to it!!!

The only part Distilled water has to play in a drop checker is if you are making your own 4dKH using Distilled water and Bicarb.

The 4dKH is what you put in the drop checker (not DI and not Tank water) then just add required amount of bromo blue (more gives a deeper colour intensity but will still make blue/green/yellow indications)

A confused Andy


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## Homer_Simpson (Apr 2, 2007)

Supercoley1 said:


> If BlackSunshines drop checker came with the proper 4dKH solution then I don't understand why he is adding DI water to it!!!
> 
> The only part Distilled water has to play in a drop checker is if you are making your own 4dKH using Distilled water and Bicarb.
> 
> ...


Thanks for your help, no point dragging this out. I figured out the solution to my problem. I did not post to have a lengthy debate about these issues.

As far as BlackShine is concerned, my point is simple. I would rather purchase a drop checker and solution from someone who already includes the proper solution with the drop checker rather than paying more to buy one from someone who includes a solution that serves no function and requires me to monkey around preparing a special baking soda distilled water solution. I prepared such a solution in this case only because I was driven by my impatience, not something that I enjoy or could really be bothered with.

Peace

P.S. Mods - please close/lock this thread. I have my answer. Thank you.


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