Drop Checker Help Please

[taffia1]

Morning all,
I had an old drop checker that was supposed to be filled with a few mils of tank water then 2 drops of the reagent.  I've set up a new tank and bought some bromothymol blue.
 
I have only put bromothymol blue in my drop checker (the same few mils that was supposed to be filled with tank water and 2 extra drops to keep the level consistant.  After injecting some co2 the drop checker turned from blue to clear?? I thought it was either supposed to be blue green or yellow.
 
What does this mean because it's clear, is it a really really light form of yellow?
 
Am I using it correctly?, should I put tank water in my drop checker with 2 drops of bromothymol blue or is it only bromothymol blue that goes into the drop checker?
 
I bought the bromothymol blue online from a reputable aquatic store so I don't think it's a problem with the solution mixture.
 
Please help

 

[techen]

You must use both blue and anther fluid I can't remember the name of. You can get pre mix3d solutions off ebay which I used. Turned from blue to green when co2 was good.

Also don't put tank water in the drop checker. Just the solution.

 

[taffia1]

Sorry It's the 4dkh solution with bromothymol blue so the soulution should be ready to use, or at least it should be.  Maybe I need to check.

 

[DrRob]

Drop checker shouldn't really go clear, but some of the premixed ones are a tad weak for my liking and the greens and yellows don't stand out all that much.
 
Also worth taking a look at the drop checker itself, some of the ones with seals are capable of leaking, which is annoying, although most of them are solid glass now. If they leak they'll definitely go clear, although it doesn't seem to bother the fish.
 
Otherwise, indeed, no tank water at all, a drop checker is designed to show the pH shift in a sample of known hardness (in this case 4dKH) and at that point the green state is 30ppm of CO2.