# The Best Drop Checker Solution



## jmowbray

You will need to buy/make your own 4dkh solution and add the pH reagent to it.


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## Darkblade48

As mentioned, you will need to add a 4 dkH reference solution to your drop checker. In addition, you will need to add a few drops of the pH indicator reagent that you received (it is bromothymol blue). 

Here are some instructions written by billionzz on how to make a 4 dkH reference solution.
http://www.plantedtank.net/forums/general-planted-tank-discussion/42429-kh-standard-how.html


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## DarkCobra

I probably have the same drop checker from an Ebay seller in Hong Kong.

There's someone who regularly sells 4 DKH solutions on Ebay, and I purchased mine from them. When I start running low, I'll mix my own and compare it against the purchased one, so I can make sure I've mixed it correctly.

Throw out the indicator drops that came with the drop checker. Use the pH indicator from your pH test kit instead. The stuff that came with my drop checker gives different and presumably faulty results.


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## JRMott

DarkCobra said:


> I probably have the same drop checker from an Ebay seller in Hong Kong.
> 
> There's someone who regularly sells 4 DKH solutions on Ebay, and I purchased mine from them. When I start running low, I'll mix my own and compare it against the purchased one, so I can make sure I've mixed it correctly.


I think I ordered the same stuff as you darkcobra, haven't tried it yet but just ordered the 4 DKH solution off ebay. It was pretty cheap, I think around 7 dollars, and should last a long time. IMO, not worth making your own unless you use a lot of the stuff.


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## Swan900

I will throw the pH reagent that came with it then. TBH I didnt trust it anyway due to the Chinese writting on it and the doggy instructions. But many have told me the drop checker itself is good, just not the rest.


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## herns

> I probably have the same drop checker from an Ebay seller in Hong Kong.
> 
> There's someone who regularly sells 4 DKH solutions on Ebay, and I purchased mine from them.
> 
> Throw out the indicator drops that came with the drop checker. Use the pH indicator from your pH test kit instead.


I have the same drop checker bought from Ebay seller in HK. It uses a Co2 test reagent.
The instruction says to place 3-4 drops of this CO2 Test Reagent into the ball side of the tester. #3 further says "...Place some aquarium water in the tester (amount of water needed is to fill up to half of the ball".

So, what I've learned is to get a 4kdh solution instead of using the CO2 Test Reagent that comes with drop checker and add PH drops like this one instead of aquarium water. Is that correct?


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## DarkCobra

herns said:


> So, what I've learned is to get a 4kdh solution instead of using the CO2 Test Reagent that comes with drop checker and add PH drops like this one instead of aquarium water. Is that correct?


Almost, but backwards.

The pH drops replace the test reagent. 3-4 drops seem to work nicely. Add an extra drop or two if you want darker color, it won't hurt anything.

And the 4 DKH solution replaces the aquarium water. Use that to fill the glass ball to halfway or so, after adding the pH drops.

Maybe the included test reagent has been modified somehow to make it read more accurately with average aquarium water; which would explain why it reads different. If so, it's a noble but ultimately useless attempt, since aquarium water can differ greatly.


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## herns

> Almost, but backwards.


:biggrin:LOL!:biggrin:



> The pH drops replace the test reagent. 3-4 drops seem to work nicely. Add an extra drop or two if you want darker color, it won't hurt anything.
> 
> And the 4 DKH solution replaces the aquarium water. Use that to fill the glass ball to halfway or so, after adding the pH drops.
> 
> Maybe the included test reagent has been modified somehow to make it read more accurately with average aquarium water; which would explain why it reads different. If so, it's a noble but ultimately useless attempt, since aquarium water can differ greatly.


Thanks for clarifying this for me.roud:


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## Swan900

How do you make your own 4DKH solution then to save me from purchasing a bottle of the stuff? Thanks!

Swan


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## DarkCobra

Instruction link posted by Darkblade48 in the second reply to this thread.

It requires some accurate measurements, which some people have circumvented by scaling up the recipe; resulting in gallons of 4 DKH solution. :hihi:

Also, there's some debate whether differing amounts of atmospheric moisture absorbed by baking soda will throw the weight measurements enough to render the solution inaccurate.

That's why I bought my initial bottle of 4 DKH solution, so I'll have a reference to test my homemade solution against later.

You could also use a KH test kit, which will verify your 4 DKH within +/-0.5°, which is probably good enough for most people.


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## hbosman

Swan900 said:


> Ive recently had my drop checker arive and I have installed it in my tank so I can get a proper reading for my CO2.
> 
> The product came from Hong-Kong on eBay and came with a pH Reagent to use as the colour change indicator for CO2 levels. I dont think this is the 4dkh solution that I should be using. But I have also read that I should add 3 drops of pH reagent to it anyway?
> 
> So please let me know what I need to add to my drop checker to give me an accurate reading! Thanks!
> 
> Swan


Just a question. Looking at your avatar. Is that a KFC bucket on your head? :biggrin:


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## herns

hbosman said:


> Just a question. Looking at your avatar. Is that a KFC bucket on your head? :biggrin:


LOL! I didnt notice that.:hihi:


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## DtEW

DarkCobra said:


> Maybe the included test reagent has been modified somehow to make it read more accurately with average aquarium water; which would explain why it reads different. If so, it's a noble but ultimately useless attempt, since aquarium water can differ greatly.


This seems to be an Asian thing, as the ADA drop checker w/included pH solution I have features more-or-less the same recommendation: use aquarium water.

However, using aquarium water never gave me a reading anything anything close to what I got with my Hagen test kit. When I switched to 4dKH water, the drop checker status was more in-line with my test kit.


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## DarkCobra

hbosman said:


> Just a question. Looking at your avatar. Is that a KFC bucket on your head? :biggrin:


You've never seen (or listened to) Buckethead before? :hihi:

http://www.youtube.com/watch?v=BGt4J9oBKKo

An odd fellow. Good musician though!


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## Darkblade48

DarkCobra said:


> Also, there's some debate whether differing amounts of atmospheric moisture absorbed by baking soda will throw the weight measurements enough to render the solution inaccurate.


Fresh baking soda is the best, as it has not absorbed much water. If you are using older baking soda, it will be more hydrated, and then you will run into issues of getting a lower kH solution than you think.

Drying does not work either, because you could run into the problem of the bicarbonate decomposing to carbonate. 

Of course, one could easily skip all of this by making the reference solution from sodium carbonate, but it is not as easily found as the bicarbonate.

Alternatively, if you have access to a lab, then you can always order up a fresh bottle of reagent grade sodium bicarbonate from Sigma 



DarkCobra said:


> You could also use a KH test kit, which will verify your 4 DKH within +/-0.5°, which is probably good enough for most people.


It is also possible to verify the kH to +/- 0.25 (or even more precise). All you need to do is double the volume that is being titrated against. You will need to increase the number of drops you are adding, but each drop will correspond to an increase of 0.5 dkH.


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## DarkCobra

Darkblade48 said:


> It is also possible to verify the kH to +/- 0.25 (or even more precise). All you need to do is double the volume that is being titrated against. You will need to increase the number of drops you are adding, but each drop will correspond to an increase of 0.5 dkH.


I am slapping myself right now for not thinking of that. Thanks for the tip!


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## DevonCloud

DtEW said:


> This seems to be an Asian thing, as the ADA drop checker w/included pH solution I have features more-or-less the same recommendation: use aquarium water.
> 
> However, using aquarium water never gave me a reading anything anything close to what I got with my Hagen test kit. When I switched to 4dKH water, the drop checker status was more in-line with my test kit.


Not so much an Asian thing as my DC from RedSea said the same thing. Tells you to use aquarium water. I've made my own 4 dkH solution using the instructions in the link and it works great, but after a while, I've noticed the KH seems to go up by a degree or two.


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## Darkblade48

If you have the solution well sealed and are sure you are not losing any water due to evaporation, there should be no reason why the alkalinity of the reference solution goes up.


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## fluff34567

why mess about adding water or solution when you can just use something like this??

http://www.dennerle.eu/global/index...ct-ph&catid=123:profi-line&Itemid=153&lang=en


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## hbosman

DarkCobra said:


> You've never seen (or listened to) Buckethead before? :hihi:
> 
> http://www.youtube.com/watch?v=BGt4J9oBKKo
> 
> An odd fellow. Good musician though!


Amazing! Thanks for posting.


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## JRMott

So are we saying to ditch the asian reference solution and use pH solution from our test kits?


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## Darkblade48

fluff34567 said:


> why mess about adding water or solution when you can just use something like this??
> 
> http://www.dennerle.eu/global/index...ct-ph&catid=123:profi-line&Itemid=153&lang=en


Because we are like to save money 



JRMott said:


> So are we saying to ditch the asian reference solution and use pH solution from our test kits?


A reference solution and the pH solution are two different reagents. Most Asian bought kits tell you to use aquarium water and their test reagent. 

You can use 4 dkH reference solution and bromothymol blue (the active reagent in the API pH test kit; or you can mix up your own) to replace both.


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## herns

How do you clean the ball of the drop checker?


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## Darkblade48

Bleach always seems to work, followed by a good bath in 2-3x the recommended dosage of Prime.


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## herns

Darkblade48 said:


> Bleach always seems to work, followed by a good bath in 2-3x the recommended dosage of Prime.


Do you soak the drop checker for few hours with bleach or just rinse it?


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## Darkblade48

herns said:


> Do you soak the drop checker for few hours with bleach or just rinse it?


Depends on how dirty the drop checker is. Usually, I leave it in for however long it takes for me to do a water change (maybe 30 minutes - 1 hour).

I use the same process for my diffuser.


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