I searched FAQ's and Forum on my question but didn't really get an answer. We've had an FNS DE vertical grid filter for several years. When I close the pool for the season I've always sprayed the grid filter with water to remove as much DE as possible. Then, I soak the filter for a day or so in a large trash can containing a light mixture of TSP and water. I would like to know if there's something else I can soak it in. The TSP doesn't seem to do anything for breaking down the material still clinging to the filter that I can't get to with the hose. Thank you very much.