http://www.askthepoolguy.net, http://www.facebook.com/askthepoolguy – some of our viewers wonder how often the sand should be changed in their sand filter. The Pool Guy has recommendations for you: change the sand in a sand filter when your system tells you it’s time through your water clairty and its ability to clean the pool, or if it’s been more than 3-5 years since it was changed or when you can see the signs in the sand.