In addition to what Watermom said regarding when to shock your pool, a dead give-away is chlorine loss overnight. But you have to have a reliable accurate way to measure chlorine in order to use this tool. So...I second the advice to get the good kit!! It may seem a little expensive right now, but believe me when I say it will save you hundreds of dollars and lots of headaches, just in your first season alone.

Congratulations on the new house and pool!

Janet