Again, I think the a major "key" to recommending a sol'n for you is related to your constraints (read $ or power)

If it was me, and $ was the issue (and had a decent 110v power source) you could pipe something like this into the tote:

Aquarium filter which will cycle 525gph, include charcoal filtration (you have to source the activated carbon) and includes course/fine screening and include a 9w UV lamp ($10 bulb replacement @ ~2-3 years).

That said this is totally a "hill billy" solution but its under a $150 and you are up and running.