I don't know if this is normal?

So I finally got my first kegerator therefor i am also kegging my california common for the first time. I trying the burst carb method. I hooked up the gas and cranked the co2 to 30psi. Left it all day with the gas open at 30psi. Before i went to bed i closed the line that way if something broke while i was a sleep it didn't damage anything. Opened it back up this morning and checked my gauges. When i started yesterday one of the gauges read 1700psi in the 2.5lb co2 tank and this morning it reads just below 500lb. Is this normal. Does anyone know where i could have gone wrong. I don't think the keg is leaking. I tested it a few times before i put beer in it.
Thanks

If your tank is in the cooler than yes it is normal for it to read considerably lower.

The high pressure gauge does not mean much. If you put the tank in the fridge, it will go down. But do not rely on it. The only thing it indicates pretty well is when the tank is empty, but before that, it will not be accurate.

The only way to know accurately how much CO2 you have left is to weight the tank.

Ok good to know i would rdwhahb but this all that i have brewed right now.