Ratlung. Worse than we thought.

[Eric1600]

Tink that probably wouldn't work for two reasons. Light intensity decreases with the square of the distance. Thats way UV systems are long reflective cylinders to keep most of the water flowing close to the light. So you'd need a really powerful set of lights. But the second problem is clarity. You'd need to remove all the particles because anything bigger than about 20 microns will block light. Statistically if it ran 24/7 the exposure rates might be high enough to get everything, but you'd have to have a lot of really bright lights and pretty clean water.