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Drop Checker

amy4342

Member
Joined
22 May 2008
Messages
338
Hi all
I've just ordered new stuff for my drop checker because I was running out. I've ordered the 4dkh and the Refil for the JBL Permenant C02 test which is labelled bromothymol blue. I've added 3ml of 4dkh solution and 3 drops of bromothymol blue, but the solution turns a dark blue. I thought it was supposed to turn green? Am I doing something wrong?
Thanks all
 

Themuleous

Member
Joined
6 Jul 2007
Messages
4,124
Location
Aston, Oxfordshire
Well you're kind of right. When you first add the brom blue to the 4dKH water it has almost no co2 in it, then when you put the drop checker in the tank, the co2 diffuses into the 4dKH water and the brom blue turns green when the tank water is 30ppm co2, or yellow if the co2 is higher, say 40ppm co2.

Thats the beauty of the drop checker and 4dKH water system, if the water in the DC is blueish it means your co2 is low, green is perfect, yellow-ish is co2 to high :)

Hope that helps

Sam
 

amy4342

Member
Thread starter
Joined
22 May 2008
Messages
338
Ah, right, I see. That explains it all - thanks Sam. I thought, because the kh4 solution was at pH7, it would be green. Didn't think about the Co2 content :oops: lol.
 

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