The sun radiates many forms of measurable light. Some have been harnessed and focused to serve various purposes, ultra violet light can be used in your tank to kill microbes such as ich and algae. If used regularly it can contribute to healthier water in a visible way. In my opinion it is certainly worth trying if you haven’t already. If you ask somebody at your LFS they might tell you that you need a light that needs to be hardwired into your tank, or that it costs hundreds of dollars. Although that is an option, it is not the only or best option for many people. You would be surprised what a low power/quality light can do for your tank.
My recommendation would be to find a cheap UV Aquarium Light (online) for $20-$40 and see for yourself. It has become very obvious at Live Gem Factory Ltd. that many people in the hobby are misinformed about what things they need and how much they should spend on equipment and tools.
We have also noticed the prices of certain products are insanely expensive because of their specialized function or consumer market. We have no dry goods/equipment for sale here. The product mentioned below is something I personally use. It is able to be moved from tank to tank and for us that has made it the choice pick.
AquaTop creates a great UV sterilizer/filter that is portable meaning you can drop it in and pull it out as desired or needed. It has plugs and switches for both the UV and filter function of their product. You can find it on your own and check it out. I think its about $100. AquaTop UV Sterilizing Pump- SP7UV.
Depending on how bad the clarity of the tank is, it may take a few days up to a week to clear.