# CO2 drop checkers & bromothymol blue



## Sim222 (22 May 2008)

Can anyone tell me if API PH Test Kits contain bromothymol blue that would work with 4dKH solution in a drop checker

thanks

Paul


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## Wolfenrook (22 May 2008)

If I remember correctly for API you want the low range liquid pH kit, not the wide range or high range ones.

Ade


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## Sim222 (22 May 2008)

thanks I have the API master test kit which includes High Range (no good) and a.n.other covers PH 6.0 to 7.6 is this other the one that is likely to be ok - as far as i can see API don't do a PH test call 'low PH'

many thanks for you help!!


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## Steve Smith (22 May 2008)

It's the Hagen Low Range that has bromo blue:

http://www.aquaessentials.co.uk/index.p ... ucts_id=81

No idea about the API


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## Wolfenrook (22 May 2008)

I just looked and couldn't find anywhere selling API low range test kits either.  I used to have one of their liquid master kits, and can tell you that the reagents supplied wont give the right colour range for using with a drop checker.

Apart from purchasing a Hagen low range pH test kit you could also buy one of the many CO2 permanent test refills, as these are usually the exact same thing, I am currently using the refills for Dupla permanent tests with 4dKH solution in mine and it gives the correct colour range.  Having looked it would actually seem that you can get the refills for the JBL permanent test for less than a Hagen low range pH kit would cost, so this may well be the more cost effective solution.  Just ignore the instructions and use it as per the usual drop checker guides.

Ade


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## Egmel (26 May 2008)

Sim222 said:
			
		

> thanks I have the API master test kit which includes High Range (no good) and a.n.other covers PH 6.0 to 7.6 is this other the one that is likely to be ok - as far as i can see API don't do a PH test call 'low PH'
> 
> many thanks for you help!!


I use the a.n.other one and it works fine, blue with no co2 and a nice limeade colour when co2 is going strong


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## beeky (4 Jun 2008)

As long as you know what colour pH 6.6 is it doesn't matter what you use. It doesn't have to be green, it's just to show that it's at pH 6.6.


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## ziggy_909 (3 Jul 2008)

hi i have just mixed my own 4dkh solution ... i hope ..!!!

i used a mixure of De ionised water and my tank water at various concentration to get 4Dkh ... total cost Â£1.00

my only problem is i have 2 bottle of reAgent and 1 bottle of ph tester... (seem to collect this stuff over the last couple of years...)

bottle 1 = wide ph test solution from a Nutrafin essential mini master test kit....(don't laugh ... got it free with a secondhand tank)...(don't think this will work as it a wide range test...!!!!) enlighten me..!!!!

bottle 2 = Dennerle co2 indicator ( got it with a co2  pressurized system) (orange in colour)

bottle 3  = co2 test  reagent, got from ebay with my very cheap drop checker (from hong kong probably.)..(bluey green colour liquid)

are any of these bromothymol blue or can i use any in my drop checker with my 4dkh water....


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## Dave Spencer (5 Jul 2008)

ziggy_909 said:
			
		

> hi i have just mixed my own 4dkh solution ... i hope ..!!!
> i used a mixure of De ionised water and my tank water at various concentration to get 4Dkh ... total cost Â£1.00



This won`t work I`m afraid. The whole point of using 100% pure water with BiCarb added is that the BiCarb is the only thing that will react to alter the pH. You are using tank water that will have all manner of reactions going on, altering the pH in the drop checker.

Dave.


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## GreenNeedle (5 Jul 2008)

Just to confirm earlier question.  The normal Ph (not the high one) in the API master kit does contain bromo and works perfectly.  Think it is the 6 to 7.6 one.

Andy


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## ziggy_909 (5 Jul 2008)

> The whole point of using 100% pure water with BiCarb added is that the BiCarb is the only thing that will react to alter the pH.



cheers for the input.... is it possible to uses biCarb of soda ( baking additive ) and if so at what concentrations....


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## GreenNeedle (5 Jul 2008)

Yes Bicarb of Soda for cooking is OK.  Baking Powder is not.  They are different.

The way to make it is 5ltrs of DI mixed with 6g of bicarb = 40dKH.
Then 90mls of fresh DI with 10ml of 40dKH = 4dKH.

Not exact but easily close enough for our purposes.  There was much debate previously about 5.99something grams and then it was 4.9something after baking (to remove any moisture) and then it was decided that baking changed the compunds so it was back to the 5.99something blah blah. lol

as close to 6 is near enough to give you an accurate enough reading.

Andy


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## ziggy_909 (5 Jul 2008)

i don't have digital scales for measuring just measuring spoon set...

can i approximate with spoon measures and test with a *testing kit*... sorry about the swear words ...


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## GreenNeedle (5 Jul 2008)

afraid not.  a measuring spoon may be approx 6 and OK for things that don't need to be accurate like ferts where 1 gram either way means nothing.

measuring spoons measure bulk and not weight!!!  a teaspoon of one substance may weigh 6g but another may weigh 4g.  This is easy to see when we measure our NPK solutions.

Therefore you need a set of scales that is accurate to 0.1g (or 0.01g which was originally suggested and I ignored. lol)

Total accuracy is not vital but it does need to be fairly accurate and a measuring spoon could be Â½g either side.  That is a huge difference on such a small quantity.

As to the test kits which test kits do you mean?  We use DCs for 2 reasons.  1 that they are a simple 1 glance check and 2 that the KH/Ph chart can give way off results.  If you have a good enough KH kit it would've cost you quite a lot of cash.

Andy


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## Ed Seeley (7 Jul 2008)

You can use a KH testing kit to get a much more accurate reading by testing larger volumes.  My Tetra kit will give a reading accurate to 1dKH when testing 5ml of water.  If you double the volume it is accurate to 0.5dKH.  I therefore doubled it again to give me a reading accurate to 0.25dKH.  I did debate going to 50ml which should be accurate to 0.1ml but was happy with 0.25dKH.  It's worked well for me anyway.


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## celkins (8 Jul 2008)

But how accurately can you differentiate the colours on a chart, as opposed to read a balance...

0.25dKH estimate is still a significant percentage error when looking at a 4dKH datum. IMHO, better to accurately weigh the sodium (bi)carbonate to make up the solution.


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## ziggy_909 (9 Jul 2008)

i have ordered some digital scales from ebay... now i have to order some ~Bromothymol blue... i see AE have started to sell the solution on its own, without having to buy the whole test kit...


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## Ed Seeley (12 Jul 2008)

celkins said:
			
		

> But how accurately can you differentiate the colours on a chart, as opposed to read a balance...



Seeing as it's simply a change from blue to yellow then pretty accurately.  You're very correct about reading the balance more accurately but Sodium Bicarbonate absorbs water once opened so you don't know quite what concentration of it you're adding with your scales!


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