Can the pressure drop faster in a large CO2 tank

[drodgers]

I hope im wording this correctly.
I just purchased a 20lb tank to replace a 5lb tank it seems to be dropping tank pressure much faster then the 5 pounder.

Nothings changed same regulator etc and i checked it for leaks.

I was under the impression bigger tanks hold their pressure longer more liquid volume etc .. or maybe i miss understood?

Any help would be great since i bought this used i would like to return it if there may be something internal that be dodgy.

 

[Vivian Andrew]

There might be a leak, if you got dual gauge regulator open the valve of your co2 tank where the pressure will show 1000 then close the valve, after closing if your pressure reduce then there is some leak after checking 1st gauge do the same with second gauage, and also use some shampoo foam to check the joints.

I got 7kg(15lb) cylinder which comes for nearly 7-8 months with 4bps 7 hours a day.