I've read posts but this still has me confused. I want to get a UV sterilizer to kill/prevent parasites in my tank. I have a 75g tank that I'm going to buy an Ehiem 2217 for and I want to buy the uv sterilizer at the same time. I would be connecting it to the outflow of the canister, which is rated 265gph, how many watts do I need to kill parasites? Some say this is more than if I wanted to kill algae?? Do filters usually flow at the rate they are rated? I was thinking of getting a Turbo Twist that many talk about but I'm open to any other suggestions. I read somewhere to kill parasites I would need 1w UV per gallon - is that 75w?!