I have a Aquatop UV Sterilizer that works great and my water is crystal clear.I picked it up on Amazon for about 47 dollars with the powerhead and UV Sterilizer that is a 10 watt bulb, rated at 210 gallons.Also you can go to truaqua.com to check out their other UV Sterilizers, but what size tank do you have?
Yes I have and use the turbo twist. I have been very happy with the results even in my large tanks. I selected this one because I can place it inline with my Fluval 5 without requiring an additional pump. I am sure there are other good products so do your research.
I tried a product called a submariner for my smaller tanks and quite frankly I think its junk dont waste your money on it.
I bought a couple Aquatop 500UV's and they work great. Got them for $114. from "Koienterprise" who is a vendor on here. Best filters I have ever had and you get double out of it then most canisters that are the same.
If you don't want to spend a arm and a leg, but will give you good results, go with Aquatop.I would stay away from Green Killing Machine though, because I had one that lasted me about 3 months and it burnt out too quick
I will admit the Green Killing Machine did make my water crystal clear, but I may of ended up with a defective one and for almost the same price of replacing parts of it, I wanted to give Aquatop a try instead to where I am getting the same exact results out of a 10 watt bulb.