AVOID ADDING TOO MUCH DE POWDER - One of the most common causes for getting DE Powder in your pool is adding too much DE powder. Check your owner's manual for the manufacturer's recommended amount of DE Powder. If this is a new installation, you will have to add the full recommended amount. But if you are replacing DE Powder after a backwash, you will not need to add the full amount - generally around 80%. The grids will have retained some of the DE Power after the backwash, and if you add too much, it may end up in the pool. Use the DE scoop that is generally provided with the DE Powder to measure the amount of DE Powder to add. A 1 lb coffee can is not equal to a 1 lb DE scoop. Another guide to assess how much DE Power to add is to monitor the pressure gauge. Stop adding DE Powder when the gauge hits your normal operational range - generally 10-13 psi.
CHECK MULTIPORT VALVE GASKET - If your Multiport Valve (MPV) Spider Gasket is damaged, you could have DE Powder leaking into the FILTER path during BACKWASH. A common cause of a damaged MPV gasket is the pool owner's failure to turn off the pump before moving the MPV handle. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" for more information.
CHECK FOR TORN GRIDS - Another common source of loose DE Powder is through a tear in the grid fabric. Remove and inspect each grid for signs of tears or a breakdown of the plastic core that has poked a hole in the fiber. Replace the grid with a new one if required. See our guide on "How To Remove and Clean Hayward DE Filter Grids" to see how to access these grids.
CHECK FOR SUCTION LEAKS - Another possible cause is backflow from the filter back though the pump and skimmer or suction ports. If there is a leak in the suction side of the piping, air can be sucked up the system and build up pressure inside the pool system while the pump is on. When the pump is shut off, this built up pressure can be released backwards into suction ports of the pool carrying some DE Powder with it. See our guide on "How to Identify and Correct Air Leaks" to check and resolve this issue.