Had an algae bloom in my tank. Water was so green and cloudy you couldn’t see to the other side of the tank. Bought this on a Sunday dropped it in and by Tuesday the water was crystal clear. I highly recommend if you’re having algae problems.

I have green water so I bought this. Been in my 30 gallon tank for 6 days and haven’t notice the slightest difference at all. Even with the lights off and this the Water is still as green as it was when I started. The only positive is that it’s very quiet but if you have green water I personally can’t recommend this product.

The Green Killing Machine makes my aquarium crystal clear! Petco has it in stock, and offered a same day free delivery option, plus a coupon.

This product worked wonders on our tank. We had an algae bloom in our 14 gallon tank. At first we thought it was a bacterial bloom so we tried a water clarifier that did nothing and kept changing out the water which did nothing. The fish weren't swimming as much or eating as much and we were pretty stressed then we tried this product. We couldn't even see the back of our tank it had gotten so bad but once we put this in the tank the water was completely cleared by day 3. Amazing. Our fish are so happy now. They're swimming around a lot and eating normally again. It slowly pulls the tank water in at the bottom and I guess the UV light kills the algae then pushes the water back out of the top snorkel looking tube. You won't be sure it's even working but you can feel it pulling in the water at the bottom where the sponge is located so we knew it was at least pulling the water in. How long it takes to clear the tank depends on how large your tank is and how much water it has to clean. It is kind of big and bulky for our little tank so we'll only use it if we start to see algae becoming a problem again instead of running it all the time. Hopefully we won't need it much. Our tank is only a couple months old and we're still learning so we'll be better about cleaning and not over feeding but I'm glad we have this product in case we have more algae issues. At the first sign of cloudy water we'll put it back in the tank and let it run for at least 24 hours or until the water is completely clear again.

After trying other methods to clear up my green aquarium water (so green you could barely see through it), I purchased the Green Killing Machine. My tank size is 55 gallons, I still went with the 9W which is for aquariums up to 50 gallons (there is significantly less water due to space from substrate, decorations, etc.). I set it up and plugged it in on a Saturday, and Wednesday morning (4 full days), the water was finally crystal clear! Definitely worth purchasing if you are struggling from green water due to algae.

I had a very green tank, couldn’t even see to the middle of it. I tried everything from large and frequent water changes, critters that eat the algae, and balancing the water parameters. Nothing worked so I bought this thing and my tank was crystal clear in 4 days. Very happy. Cannot speak on longevity since I have only had it a week, but I now have it on a timer to run a few hours a day based on some other reviews.

Garbage. I picked it up from the store when it had a broken and wet box and was assured that it would work and if it didn't then I could return it. I tried it for a few weeks and this doesn't work at all. Then I was denied a return saying it was not eligible for return. Now I'm doing a charge back from my credit card for this useless $70 item. Such a terrible experience.

I bought this for my 75 gal aquarium. The directions were to wait may be upto 2 week. By the 4th day my aquarium has never been cleaner. My fish even seem more energetic! So far so good! My aquarium is my a window and so I have had on going issues with algae. This killing machine seems to have fixed that.