How do I know if propane tanks are low on propane?
I've learned that if you knock on the can you can determine the levels by the sound. If it sounds hollow it's empty.
If you are somewhat familiar with full and empty ones and they are small enough, how heavy they feel is a good indicator.
hows this? http://www.harborfreight.com/propane-level-gauge-66940.html
The bigger question is how big is your propane tank? Is it a 500 gal tank or a small one for your grill?
I found this online, no idea if it's safe or whatever...http://www.chow.com/food-news/119554/how-to-tell-how-much-propane-is-left-for-your-gas-grill/There are also stick-on liquid crystal thermometers that show the temperature difference visually.