I keep getting small (well water) particles in my 2GPM chemlawn nozzle. Its like sand or something, even after cleaning out the tank they are still there. I have the stock filter that came with the unit, the mesh has very large holes so I know something smaller should help. It looks like 50 or 80 mesh would work great but I have been reading that they clog. It will eventually have pre/post/uflexx and Fe if that helps. What works for you?