Mini GKM3W

This is a must have for anyone who owns an aquarium. One day I left for work and forgot to turn the light off in my aquarium. Yikes! Within two weeks, my water was cloudy and light green in color. Just FYI, I do 1/3 water changes every week, vacuum the substrate, and wipe down the walls of the aquarium. My water has always been crystal clear so this was a huge departure from what I am used to. Needless to say, I wanted to clear this up as quickly and carefully as possible. I searched around Amazon and the internet and came upon this gem called "Little Green Killing Machine". I thought that is was reasonably priced to allow me to try it and not break the bank if it did not work. So, my expectations were level set going into it. WELL! This little machine cleaned my water in about 4 hours. CRYSTAL CLEAN AGAIN! I really could not believe it. I decided to keep it running for a week and just about 5 days ago, I removed it. I was bracing myself for the return of the cloudiness/algae. It has not returned. My tank is so clear and I am so grateful the this Little Green Killing Machine. I really think this should be included in any start up bundle for a novice aquarium owner like myself. The item over delivered for an outrageously fair price with fast shipping and complete satisfaction. as an aside, I have a BioOrb 4 gallon vertical tank and it fit perfectly.

3 days to fully clear! After an algae bloom due to pH drop following a re-escape of my Fluval Spec V, my aquarium was in desperate need of a little bit of assistance. This product is amazing —see the before and after photos. This was after only 72 hours in the aquarium, three days total from the first picture to the second picture. The only complaint that I have is that the unit is just slightly too large to fit into the back compartment instead of the stock pump.

Omg I rarely write reviews. I was At a loss. No matter what I did my poor fish tank was so green I Couldn’t see through it! I ask ChatGPT what was going from and it recommended this product and just days later whole tank crystal clear!!! Never had a solution for a tank work so well so quickly!

I got this GKM for my 10 gallon long tank as well as the next size up (9W) for a larger tank. This 3W sterilizer is barely smaller than the 9 W. I’m actually debating whether I should just get the larger sterilizer even for my 10 gallon. Pros: 1) Adjustable flow 2) A bit shorter than the 9W version (though really not by much, depending on how you install it) . 3) VERY quiet. 4) Sponge filter insert seems like it could keep out baby shrimp (though I only just put shrimp in my tank a couple of days ago). You could always but a finer pored sponge, instead. The flow is so powerful that I doubt that it would cause a problem with the function to replace with the finer sponge (remember that SLOWER flow through the filter exposes the problem organisms longer to the UV light, resulting in better effectiveness). 5) This is practically “plug and play” in terms of ease of use. The greatest challenge may be finding enough depth in the tank to place it. It’s really convenient not to have to need a canister filter to use this, the way you need to with so many other models. 6) No risk of accidentally looking into the UV bulb, which could potentially blind you. This is no exaggeration — I know because I’m an eye doctor. Cons: 1) Bulky both vertically and in width. 2) You need TWO OUTLETS for this one device. I’m not sure why they didn’t just do the same thing as for the 9W GKM and have both cords connect to a box that then only uses one outlet. 🤷‍♀️ This is annoying and messy, not to mention using up outlets. 3) This may or may not be a level 2 UV sterilizer, meaning that it will kill free floating algal blooms, as the name claims, but it may or may not be powerful enough to neutralize (messing up DNA of) bacteria and probably does not kill parasites (such as ich). It’s not clear if these devices have even been tested for the later two purposes. 4) Considering that this may be barely above a level 1 UV sterilizer, it’s rather on the pricey side, especially since down the road you will have to replace the bulb and casing, which cost almost as much as the entire machine. 5) I get that you don’t have to worry about the casing degrading with UV exposure over time, since you have to replace that whole section at once, but I question how environmentally friendly this approach is. That being said, it is safer than having to handle the UV bulb.

Ended up returning mine to get another color. But the product is top notch and I'd recommend it for anyone wanting color in their case. As for the UV it's a bit dim and puts out a lot of purple light which I'm told is normal. I asked about using lower band UV but everyone in the forums seemed to think I was wanting to hook it up to a 2000w supply and cook the house or something. So my search for low power emitters that will actually fluoresce my loop but not fill the case with purple continues (black case, red lights btw so purple is right out). But the product is made well and has handy magnets. Hooks right up and worked like a champ. Nothing but positive things to say about it.

Bought this for my turtle tank. Fighting bad algae for months now. The algae killer liquid you buy from pet stores doesn't put a dent in how bad it was. Even pouring half a bottle (way more than needed) at a time. I would even empty out the entire tank, and spray bleach on the walls and wipe them down and the algae would still come back in a week or two. Bought this UV algae killer on a prayer. Put it in and ran it for a few weeks. No change. I looked at the "control box" for the light, and the LED was lit up green which means the bulb is on. But under closer inspection it turns out the bulb was in fact NOT on. So the 2 weeks it was running it wasn't doing anything but churning the water. Amazon did an even exchange for me and I put in the new one which has been running for about 2 weeks now. Huge change as you can see in the photos. The water is still cloudy but that's expected as its killing all the algae. I need to clean and replace the tanks filter media. Attached are 3 photos of it. 2 before, one showing it in the tank and running on day 1. And the 3rd photo is after roughly 2 weeks of 24/7 running. Mind you this is rated for 20 gallons and this tank to its current fill level is 20 gallons so its running max capacity. I would give it 5 stars for how its worked so far but because the first one I received was defective I'm only giving it 3 stars. God knows how long this bulb will last, and potentially give me a false LED reading on the control box like the first one.

Do not recommend. I gave it 3 weeks to work and my tank is still green. This was too expensive to be so ineffective.

As many other reviews state, this device does what its states. We have a 20 gallon tank. We were away on vacation and it got warm while we were gone. We came home to the worst algae bloom we have ever encountered and knew no number of frequent filter and water changes were going to solve this problem. We have snails as part of our tank and didn’t want to use algaecides as they can harm shellfish. So we went with this based on reviews and a week later the tank was crystal clear. Wish we would have bought this years earlier instead of battling these warm weather algae blooms. Before and after pics included.

Really worked to remove green bloom. Use it every so often now

C'est très exceptionnel que j'écris un commentaire. Cela fait des années que je cherche une solution pour mon aquarium de 40 litres à ce problème d'eau. Avec cet appareil, j'ai enfin trouvé LA solution. Voyez sur les photos le avant - après au bout de quelques jours. J'avais essayé de nombreux produits anti-algues, anti-etc... Rien ne fonctionnait bien. Cette fois-ci, l'eau est cristalline comme elle ne l'a jamais été. Je vous le recommande donc fortement.

WOW, just wow!! Our 10 gallon column tank went from a murky swamp to crystal clear in a week, such an awesome product!

Fantastic !! After cleaning the glass from algae, within an hour my aquarium was crystal clear

For the first time ever, I had one aquarium go through horrible algae bloom where I could not see any fish or plant even with flash light. I bought this for that tank 20 gallon long. And for the first 2 days I saw very little change. 3rd day I could see improvement but it seemed like it would take a month to clear it all up. 4th day it was definitely much better where I could actually see most of the aquarium now. 5th day is very all clear but very cloudy like, white fog during bacterial bloom. 5th day which is today, the water is crystal clear. I'm beyond shocked how fast it worked after about 3, 4 days. I have been running it for 24 hours. I'll run it for another 3~5 days and I'll be using this on my other tanks to get crystal clear water.