Unfortunately, most people on this site who have used the "frog" system have not had good experiences.
Through time, real life testing, and the miracle of modern science, the people on this forum have found that the things needed to maintain the chemistry of your pool are simple. This is all covered in Pool School as linked in posts above, but I will give you the short version.
1. Get a good test kit. Taylor makes one, and the owner of this site sells one through an affiliated website. Both are great, the TF100 is a better value (IMHO). Testing your pool gives you the status of your pool NOW, and using
http://www.poolcalculator.com you can target specific levels of the needed chemicals to put in to reach predefined target levels.
2. The chemicals you need can be found at your local grocery and hardware store. They are:
a)bleach
b)baking soda
c)Borax
d)muriatic acid.
3. You measure your pool with the test kit, plug in your results and such to the pool calculator website, and add the amounts it calculates, and within days you have a sparkling pool.
4. Wash rinse repeat for many years to come.
The driving force behind all this was cost. Some pool stores and even some builders have very little idea about water chemistry, or any financially driven desire to educate you about it, BECAUSE THE MAKE MONEY SELLING YOU CHEMICALS.
I know several people who spend many hundreds if not thousands a year on pool maintenance chemicals. Since building my pool, I have spent about $65 on chemicals to maintain my pool. Most of that being acid, because my pool is new plaster and the ph rises in those over the first year.
Get reading and understanding whats going on in your pool and take control. Then start planning what to spend the money you save on.