Would recommend either do a closed loop in tank. Meaning pump in tank, through uv, back to tank
Or
In sump. Pump on one side of fuge, throu uv, back to sump on other side of fuge, closer to return pump. This way whatever water that goes throu uv will not go throu fuge. Which will slow down flow in fuge, increase nutrient uptake.
Maxi jet 600 on 15 watt uv will kill algae and bacteria, but you need a smaller pump to kill parasites. To kill parasites you want the flow around 75 gph for 15 watt uv, and your maxi jet is twice that.
When you position uv make it so the water outlet coming out of uv is higher than the one with the pump conected to it. And make it so the outlet is facing up, so air doesn't get trapped in uv unit