Try running on recirc the first 2 days of the SLAM, then turn off pump for a few hours to let the dead algae settle, then vacuum to waste before you start filtering. Saves me a TON of DE, backwashing and hassle. After your water is clear, break down your DE filter, clean the inserts, reassemble, and load up a full charge of DE. Rain will actually help by refilling the water lost from vacuuming to waste and backwashing for free. Don't forget to check and clean your pump basket before replacing DE or you'll have a basket full of mud.