Thank you so much for your replies. I will try to read up on all the prior posts to educate myself as much as possible. My first pool was put in about 4 years ago and I maintained it (no problems) for 2 years with Bens kit and the advice of this forum. We moved to our new home 2 years ago (knowing that we would have to put another pool in when we could afford to do it). This pool is twice the size and we are really excited. Although I feel like I forgot everything about pool chemistry! So I am back on the forum trying to re-educate myself, ordered a new kit from Ben, and just needed to find out the difference the SWG would make. So I appreciate your quick responses.