# Drop checker fluid



## amoran45 (6 Oct 2015)

I lost the bottle of fluid to fill up my drip checker....I've read somewhere u can make your own fluid.

If I make some 4dkh water, do I only need to add the ph reagent to it or is there something else I need to get? Some posts I read talk about some brothymyl blue also....is this a different chemical I need ?

Any info would be greatly appreciated!

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## rebel (6 Oct 2015)

My understanding is that you add a few drops of pH indicator solution until it goes very blue. This forms the 'reference value'. If this later goes green in your tank you have approx 30ppm of co2. Yellow may mean too much.. Ball park of course. Watch your fish at all times.


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## ian_m (6 Oct 2015)

You can make your own 4kdh water quite easily, though may be cheaper and convenient to buy a small bottle.

You mix 12g of sodium bicarbonate in 1 litre of distilled water (or RO water). This make a 400dKH solution, you keep as your stock solution.

You then add 10ml of stock solution to 990ml of distilled water (or RO water) to make it 4dKH solution. You then add your bromothymol blue to this solution. Done.

4dKH solution. 
https://www.aquaessentials.co.uk/ne...9.html?zenid=37e2ccc08a1c29054e25cc5f9b728f65

Bromothymol blue.
https://www.aquaessentials.co.uk/ne...5.html?zenid=37e2ccc08a1c29054e25cc5f9b728f65


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## amoran45 (6 Oct 2015)

ian_m said:


> You can make your own 4kdh water quite easily, though may be cheaper and convenient to buy a small bottle.
> 
> You mix 12g of sodium bicarbonate in 1 litre of distilled water (or RO water). This make a 400dKH solution, you keep as your stock solution.
> 
> ...


I've also read that u can use the ph test solution from a testing kit to add to the 4dkh solution...is that bromthymol? 

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## ian_m (7 Oct 2015)

amoran45 said:


> I've also read that u can use the ph test solution from a testing kit to add to the 4dkh solution...is that bromthymol?


Er no. Bromothymol blue is a very narrow range indicator going from blue at 7pH to yellow at 6pH with green in between (6.5pH), so gives a very good colour change in a narrow pH range. You could use your pH testing solution but they are very broad range ie Litnus changes colour between 4.5pH and 8.5pH so you would have to determine the exact colour at 6.5pH which would be very hard.


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## amoran45 (7 Oct 2015)

ian_m said:


> Er no. Bromothymol blue is a very narrow range indicator going from blue at 7pH to yellow at 6pH with green in between (6.5pH), so gives a very good colour change in a narrow pH range. You could use your pH testing solution but they are very broad range ie Litnus changes colour between 4.5pH and 8.5pH so you would have to determine the exact colour at 6.5pH which would be very hard.


I see.....thanks for the info! I guess I'll have to find some bromothymol blue then....I'm sure I can find some in canada

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## xim (7 Oct 2015)

I think the Tetra pH test kit contains bromothymol blue, the resulting colours match it.
See which other brands of pH test kit some people here use in the DC, in case one of them 
may be easy to find in your area.
http://www.ukaps.org/forum/threads/co2-drop-checkers-bromothymol-blue.1724/


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## amoran45 (8 Oct 2015)

One more question....I have found some btb to purchase on amazon...but I have found different percentages of aqueous solution.....I there one in particular that would be more accurate? Or does it even matter? Thanks again

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## ian_m (9 Oct 2015)

Doesn't matter. Just gives a more or less opaquer green at 30ppm. With a glass drop checker, before I broke it, required quite a concentrated solution but with JBL drop checker I dilute with 4dKH water a bit so I can easily see the white background.


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## zozo (9 Oct 2015)

I juse the JBL pH 6,0 - 7,6 sollution in the drop checker. Next to a PH controler. 
With 4dKH it starts dark Blue and gets a nice clear green collor at pH 6.4 - 6,3.. Which is my goal value.
If i use a wider range test sollution one from pH5 to 10, the color differs quite a lot it starts dark green and turns more to the yellow at pH6.4
My tap and tank water is already between KH 4 - 5..


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## amoran45 (10 Oct 2015)

Alright sounds good, thanks for all the info!

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