CO2 Pressure Dropping?

I just did my first kegging last night. Went really smoothly. I cleaned and sanitized it earlier in the day and checked to see if there were any leaks and it didnt appear to be any. I set the beer at 13 psi and I am planning on just letting it sit about a week. I went to check on it this morning and the regulator showed a drop in pressure in the CO2 tank. When I got the tank it was at about 600 on the regulator guage. This morning its just about the red. I checked the connections again with soap bubbles to see if i could find any leaks and cant. Someone help, whats going on? What should I be checking that I am missing? Its a 5# tank, How long will that usually last?

If it is in your kegerator the low temperature will make it read low (about 400.)

Either that or you have a leak

Ok so it being 42 Deg will lower it right above the red "Oh sh*t you better refill" line?

Yes, when I put my in the fridge, the gauge read very low.

Ok great thanks. I swear I overreact on everything beer. I am usually a really calm person but beer gets me so worried. I guess that means its important to me haha. Thanks again for the help.

yep. room temp (70F) your psi in the tank is close to 900psi...but at beer serving temps, its usually under 500psi.

gas just exerts less pressure as it gets cold...which is why warm/hot cans of soda practically explode when you open them

by the same token, the colder a liquid gets, the more CO2 it can hold, even at non-saturation levels. this means: your beer is better, especially bottled beer, if it is chilled 2-3 days before being opened. 4 hours will cool the beer, but then that colder liquid will accept more CO2 trapped int he headspace of the bottle, giving better carbonation.

a little off-topic, but its very useful information that a lot of people don't know.

This reminds me to check my bottle it's been a couple weeks, though it's a single line from the tank to the keg in the fridge for a couple weeks yet.