I could be way off base here. BUT. IF the particle size is the problem clogging up the system, why can't you run the water through a screen system, like reefers do with a "filter sock" on their wet dry systems? OR run a DE filter as this is meant to be a water polisher and is designed to specifically remove minute particles. Would a Screen Filter reduce this as well? May reduce the nitrates and such too much though. A canister filter may work, with an extra fine filter sleeve to stop the finer particles, but the finer you go the more you have to clean it as it will plug up faster.
I have a HUGE amount of success polishing water down by passing the return lines through quilt batting (non biodegradable). I have even filtered out 'green' water in koi pond with that at the water fall. If you are going to go super anal with it, go with a bacteria screen from aqua-systems inc however this might be a bit much. I have used the bacteria screens and would only recomend them for this if you have an IMMACULATE system. Or have copious amounts of free time for constant cleaning.