Have you noticed the look of your pool water is not as clear as it used to be? Have you noticed no matter how much water clarifier you put into your pool, the water is still cloudy? Have you noticed the sanitizer level is not as stable as it used to be? Do you notice dirt or debris blowing back into your pool thru the return fitting? If you answered yes to any of these questions, when was the last time you either cleaned your sand filter or changed the sand? You should use filter cleaner each season and clean your sand. For example; if your sink becomes clogged at home, you usually use a drain cleaner to remove the problem. Same principle with a sand filter but you would use a filter cleaner. If is not a set rule when you should change your sand but a good guideline is usually every 3-5 years if you have been using a filter cleaner every season. If you do not use a filter cleaner you will need to change it more often. This time line can change based on what type of chemicals you use, amount of activity in your pool, and how often you keep the filter running. Suntan lotion and waste from your body both play a part in decreasing the effectiveness of your sand filter. When you do change your sand in the filter, it is a good time to also check the laterals that you will find in the bottom of your filter below the sand. If they are broken or cracked, be sure to replace them. Any that are broken could cause sand to blow back into your pool. You should cover these laterals with water first before adding any sand. The have sand could cause some damage to them.