SainSmart XpertMatic Aquarium Sterilizer Light, 5W Mini Submersible Sanitizer with Timer Aquarium, Waterproof Lamp Cleaning Green and Algae for Fish Tank, Pond, Swimming Pool, Saltwater, Freshwater

So far, I like this little thing. I've actually bought two. I use them primarily in my small tanks, a 5G and three 2.5Gs. Within a day, it clears the water right up! I haven't tried it in any of the larger tanks. It's a small wattage and a small unit, so I don't know how effective it would be in a tank 20G or more. But I've tried a lot of UV sterilizers, and most of them leaked. These are not like that. They just hang on the inside, and water flows through them as the currents in the tank take it. Like I said, I have two, so I use one in a couple of small tanks, clear up that water and move them to another if needed.

this is by FAR the best UV light I have ever owned. FORGET the ones that are also a pump/filter... this one (as opposed to those) is maintenance-free. I place it close enough to the current created by my pump/filter so that water GENTLY circulates through it, and that's it! (IF you do not place it near a current, it won't clear tank... needs to access all of the water)

Arrived fast, and easy to use. It has cleared up our aquarium within 3 days, running it 24 hours. We have now turned it down to 6 hours a day. Very pleased.

DO NOT BUY FROM THIS COMPANY. BEEN ONLINE OVER AN HOUR FOR REPLACEMENT BULB....NO WAY TO REACH THEM OTHER THAN EMAIL.....JUNK JUNK JUNK

Installed right away inside the filter area of my aquarium with a setting of 4 hours of being on. The water is looking less green. Thinking another week and my tank will be as expected. It is a 23 gallon tank

I've been keeping fish on and off for decades. Recently, I had an issue in my fully cycled 29 gallon tank that has been operating without issue for a full year. The water suddenly turned murky, then green. Research pointed me to a UV sterilizer, and I bought this one.The manufacturer says "not recommended for 24 hour use", so at first I ran it for 6 hours - not much of a change - bumped it up to 12, again, little (but some) improvement. I finally bit the bullet and set it for a continuous 24 hour run. In 5 days, the water was pristine, easily the clearest it is ever been.I believed the recommendation to avoid 24 hours is due to the bulb life - this little baby will burn out quickly at that rate, probably within 6 months. I plan to try a 12 hour cycle, and if the water stays clear, maybe bring it down to 6 hours. But one thing is for sure - this has become a permanent fixture in my aquarium setup, now that I've learned all it can do. And, I'll be buying one for my quarantine tank, since it's a great way to clear ich and other disease causing bacteria.At this price point, I have no issue replacing the unit every 6 months, and I love the fact that the bulb is shielded, meaning no fried inverts or fish.Happy as a clam! (or should I say snail or shrimp...)

Using this item for 10 hours a day cleared the green water out in 3 days. I will keep it going for a while longer to see if it will help limit the algae growth.I don't think it bothers the fish, snails or shrimp. When it comes on they do go away and stay away from it but other than that they are not acting any different.Update: After 2 months, I still love this. I have three tanks and I use this in rotation on all of them. So far, I have not noticed any issues with any of the snails, shrimp or fish. I was worried about the baby shrimp going into it as a great place to hide but so far there are no dead baby shrimp (or blind ones) falling out when I move it. Awesome purchase.

Works great. Keeps the tank clean even with the tank light on. It's compact so it fits well in my 2 gallon tank without crowding the fish. Wish I would have discovered this earlier.