Evenin to ya Ween...throw that pre-filter out. It's had it! If you try and wash it ,..ya , it will come clean but will lose it's integrity.What ive been doing Ween is i am able to grab some of that white filter mat'l that comes in a roll.It's used in big air handling units,..Neiko would know what im talkin about. Just make sure it's wide enough to completely cover the filter. Please don't wait to get that taken care of Ween,..if you keep that clean and fresh, the actual filter will last ,..well, mine is going on 6 yrs. now coupled to a Ostberg 6inch , inline,...running at between 70 - 80 %. bestest combo, .