We all understand! It takes a while for all the chemistry to make sense - especially when you listen to pool stores. Look through the swimming pool tips on the pool solutions web site:
http://www.poolsolutions.com/tips/10things.html
It will help explain pool chemistry better for you. Getting the test kit from this site also makes taking care of your own pool easier. You will find that once you get your water balanced, it will be very quick to check your levels and keep a clean pool. When you get the chemistry straight in your mind, you will understand how to balance your pool. Feel free to ask any questions - all you really need to keep in stock is bleach, borax, baking soda, muriatic acid, and stabilizer (for the beginning of the year) and a sequestering agent if you have any metals in your water.