Sand Leaking From Filter into Pool. When my filter is running I am experiencing sand in the bottom of my pool from the filter. What can be causing that?

There is only one thing that can cause sand to come back into the pool from a sand filter. The internal assembly, called the lateral assembly, is either cracked or broken. This is an easy fix and should cost you around $70 to replace the whole thing. You need to unscrew the bottom drain cap on the filter to remove the water in the tank. Then, remove the multiport valve on top of the filter. Take a shop vac and remove the sand in the filter. If the sand hasn't been replaced in the last 3-5 years, this would be a great time to do that since you already have the sand out anyway. Then, remove the lateral assembly and inspect the entire thing. After you replace the lateral assembly, you'll need to fill the sand filter tank 1/2 full of water before adding fresh sand. This is done to cushion the laterals from the weight of the sand. Cover the hole in the top of the lateral assembly pipe with a cup or duct tape to prevent any sand from getting inside the pipe (the sand will come out into the pool if it gets into the pipe). Fill the tank 3/4 full of pool filter sand. Make sure it is genuine silica pool filter sand from a pool company. A lot of big box and home improvement stores sell play sand as filter sand. This will cause you more problems!