# bromothymol blue



## Elohim_Meth (May 8, 2010)

I've heard about 0.1% ethanol solution.


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## Lycosa (Oct 16, 2006)

I would get the .1%.. the higher the concentration, the more distinct the color changes. Either would work, but you might _see_ better results with the .1%.


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## j-gens (Dec 11, 2008)

also how long does the solution last without degradation?


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## Hoppy (Dec 24, 2005)

I would just buy an API pH test kit. That solution is made for what we use it for, so it is very likely to be done right.


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## j-gens (Dec 11, 2008)

is for my drop checker is there really any reason i shouldnt just buy bromothymol blue and make my 4dkh solution


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## j-gens (Dec 11, 2008)

and isnt bromo blue just a ph indicator? so i dont know how this wouldnt be "right"?


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## Darkblade48 (Jan 4, 2008)

Elohim_Meth said:


> I've heard about 0.1% ethanol solution.


You can make it in ethanol, but making it in water is "safer". You just need to pH it with some sodium hydroxide to get the bromothymol blue to dissolve properly. This is why I make it my solutions in the lab :icon_lol:




j-gens said:


> also how long does the solution last without degradation?


I have kept it for more than a year with no ill effects, however, I still have the dry powder on hand to make more if need be.



j-gens said:


> is for my drop checker is there really any reason i shouldnt just buy bromothymol blue and make my 4dkh solution


You can do this.



j-gens said:


> and isnt bromo blue just a ph indicator? so i dont know how this wouldnt be "right"?


Yes, it is. There is no difference between making your own bromothymol blue or using the API pH indicator, but for most people, the test kit is more available than bromothymol blue, an analytical scale, a pH meter, sodium hydroxide, etc.


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## j-gens (Dec 11, 2008)

thanks darkblade.. what percentage do you make your bromo blue aqueous solutions at? 

and just to be sure im not confused i can make my 4 dkh solution and just add some of my bromo solution to it till i have the color strong enough for my liking and then im done right?

do you keep your bromo blue at room temp for storage?


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## Hoppy (Dec 24, 2005)

There are times when DIY doesn't pay off much. This is one of those times. A single API pH test kit, used just for drop checker solution, would last you several years. Just buying the chemicals to make your own indicator solution would very likely cost you at least as much, and would be a more than lifetime supply, but the $$ savings would be very small, if any.


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## Darkblade48 (Jan 4, 2008)

j-gens said:


> thanks darkblade.. what percentage do you make your bromo blue aqueous solutions at?


I made mine at 0.1%. However, I will need to double check the pH I used. I am sure I had to use 10M NaOH to get it to dissolve.



j-gens said:


> and just to be sure im not confused i can make my 4 dkh solution and just add some of my bromo solution to it till i have the color strong enough for my liking and then im done right?


Yes.



j-gens said:


> do you keep your bromo blue at room temp for storage?


I keep both the dry powder and the liquid at room temperature.


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## Elohim_Meth (May 8, 2010)

Hoppy said:


> I would just buy an API pH test kit. That solution is made for what we use it for, so it is very likely to be done right.


Hoppy, does API pH test kit give strong enough color? How many drops of it do you add to your dropchecker ref solution?
Most of pH test kits I used were very diluted.

*Darkblade48*
I also heard of mixing Bromothymol blue with Methyl red in equal proportion. Does it make any sence?


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## Hoppy (Dec 24, 2005)

Elohim_Meth said:


> Hoppy, does API pH test kit give strong enough color? How many drops of it do you add to your dropchecker ref solution?
> Most of pH test kits I used were very diluted.
> 
> *Darkblade48*
> I also heard of mixing Bromothymol blue with Methyl red in equal proportion. Does it make any sence?


When I used a drop checker I used 2-3 drops of API pH indicator, with the bulb of the checker half full of 4 dKH water. It worked fine.


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## Darkblade48 (Jan 4, 2008)

Elohim_Meth said:


> Hoppy, does API pH test kit give strong enough color? How many drops of it do you add to your dropchecker ref solution?
> Most of pH test kits I used were very diluted.


I used to use 2-3 drops also, but found that the colouration was too weak. I have now opted to use 5-6 drops instead, and it has not affected the results of the drop checker at all. However, it has made by life much easier now.



Elohim_Meth said:


> *Darkblade48*
> I also heard of mixing Bromothymol blue with Methyl red in equal proportion. Does it make any sence?


I have not heard of this before. I do have the reagents to test, but why fix something that isn't broke?


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## FSM (Jan 13, 2009)

You should be able to use any pH indicator, as long as the desired pH is within that range (the pH in the drop checker will be 6.6 at ~30 ppm CO2 and 4 dKH). Of course, if you used a different indicator then it might show a different color at that pH. If you mix different colored indicators I think it would probably not be usable.


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