Auto Refresh is the best extension to refresh on a timer
Auto Refresh is a simple extension that refreshes a page automatically on a given interval. There are many extensions to do this but this one is the most straight forward, and easiest to use while still allowing for customization! You can customize the default time and have separate timers running for all of your tabs.
Set your refresh time by clicking the refresh icon in your toolbar, setting the minutes & seconds, and hitting start. You can stop the timer at anytime by hitting the stop button.