Review on 🐠 11W Waterproof Submersible Lamp for Aquariums and Ponds - Clears Green Algae and Purifies Water (HUV-11) by Laura Bobzien

Firstly they wear out. In fact, they are similar to the lamps used in a solarium. Even if you can see visible light, that doesn't mean UV is as strong as it used to be. If he worked constantly, I would not give him more than 3 months of life. They work really well, I run mine in a hidden area of my swamp 3 hours a day on a timer. This helps inhibit algae growth and also kills any floating parasites in the water column. This lamp must be in a low flow area to function properly and be invisible to the naked eye.