Yes, if you turned it up to 20 initially, and then turn it down, you will not see the result of turning it down until you release the c02 pressure built up in the line/guage. Another way to 'bleed' the co2 is simply to pour yourself a beer 
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Sometimes when I reflect back on all the beer I drink I feel ashamed.
Then I look into the glass and think about the workers in the brewery
and all of their hopes and dreams. If I didn't drink this beer, they might
be out of work and their dreams would be shattered. Then I say to myself,
"It is better that I drink this beer and let their dreams come true than
be selfish and worry about my liver."
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