Good afternoon, Nick - Thanks for writing to Watkins about cleaning TriX filters. Because the filters are not made of flexible material, it is difficult to clean debris from deep in the folds. Using a power washer may help remove some of it, but will tend to push most of it deeper into the folds.
If you not already, soak the filters in a filter degreaser - available from your locally authorized spa dealer and sometimes from Home Depot or Lowe's type stores. You can also soak them in a solution of water and TSP (TriChloro Phosphate) that is, many times, available at your local grocery store. I find it on the automotive aisle, in a small, bright orange box. Follow the instructions on the box for the correct measure of TSP powder to add to a 5 gallon bucket of water. Soak the filter for at least an hour and then rinse it with a garden hose. You should be good to go!