Well I decided to try it out in my sand filter in ground pool. Cleaned debris out of pool. Chlorine level up. Put hose in pool put clean water in pool. I took hot water in a bucket to filter with the duck picture dawn soap bottle. Shut pump off and open filter basket by pump squeezed quarter of it in after cleaned basket. Filled with hot water secured and turned filter on long enough to get to sand 5 seconds in filter. Shut off and switched to backwash. Let sit 20 or whatever you want all night. Turned backwash on 5 seconds put a good squeeze in the filter basket on deck to sand filter. Then let sit again 10 minutes or all night. Then kept durning on and off backwash 3 or 4 times letting it sit 3 to 5 minutes between. Then turned to rinse for 3 to 5 min or until clear water. Turned on filter. Let run 24 to 48 hours. Test chemicals then shocked and put in product called No Mor Problems. Filter 24 hours but shut off next morning to vacuum, backwash, and rinse. Not sure it worked to remove grease and grime in sand, but pool looks great so far. But just finished with rinse after dawn soap. I will test later or in morning. I plan to only do this twice a season halfway through Summer and before close pool for season. Try to update tomorrow.