Good product. Wools good. My only warning is, don't let it sit in water that is going to freeze. It will break it. I let this sit in water that didn't need to be a liquid at the time because I have two water tanks. The water froze and when I was ready to use that tank it no longer worked.

I just placed an order for another 250w K&H pond de icer. I have not found another low power pond heater that works better than this design. Unfortunately, I've also found they only last just under 2 winters. We have a 1200 gallon Koi pond in our back yard in the Upper Peninsula of Michigan. I cover the pond and install the heater in November and run it until April. This will be the fifth time in 8 years I have had to replace the heater before the season is over. I monitor the pond with a lighted indicator and remote thermometer. The most common failure is the heater trips the GFI outlet. After some near disasters I've learned when this happens it pays to have a spare on hand. I just wish it would happen when it didn't involve digging through feet of snow to replace it.

This tank heater will do a great job, but my problem is today it got up to 50 Deg F outside. This heater is going full blast heating the water that was on 45 deg f. All my other tank heaters (of different brand) had shut down but this one. I then placed an inline thermostate set at 40 deg air temp. and will see how this heater functions now.
Once the tank water gets above 32 deg f, the heater should shut down at about 35 or 40 deg.f. For this reason I did nto give this heater a great review. I love the design and fearutes of float of sink. But I want it to work properly with out being a fire hazard in my barn.

UPDATED REVIEW 9/18/15:

IMPORTANT NOTE: DO NOT USE SUBMERSIBLE AQUARIUM HEATERS OUTDOORS IN A FARM/BACKYARD CHICKEN SETTING - FIRE HAZARD!!

My original review was not favorable of this device. I have had more experience with it now that changes my view to very favorable, in fact I have revised my star rating from 4 to 5 stars.

My usage and background info: I am using this in a 5-gallon plastic bucket with horizontal chicken watering nipples in a backyard chicken setting. We have no other poultry than chickens. I live in the inland Northwest USA, where winters are pretty cold. Average winter temps are about +15F at night and the coldest I have tested the K&H de-icer is down to -9F (it works, with one important caveat).

My original review said it would not keep the nipples thawed and I switched to using a submersible aquarium heater. What I have learned since then:

* The K&H does not work with VERTICAL chicken nipples (these install on the underside of a bucket/container/pvc pipe) below +18F.
* The K&H works great with the HORIZONTAL chicken nipples (these install on the side of the container). I have tested down to -9F and others have confirmed down to -20F, using the same nipples and de-icer).
* The horizontal nipples only work with chicks and chickens, won't work with ducks/geese but probably will with turkeys or other birds.
* A submersible aquarium heater IS NOT SAFE TO USE OUTDOORS AND MAY START A FIRE (more below on this).

For a good discussion on the differences between the Vertical and Horizontal chicken nipples (with photos), try this link: http://www.backyardchickens.com/t/843040/vertical-gravity-vs-horizontal-spring-loaded-watering-nipples . If the link does work, then go to backyardchickens dot com and search for "vertical vs horizontal nipple" and you will find the thread discussion.

About the fire danger: the short version is a submersible aquarium heater nearly started a fire in our chicken coop when the bucket ran dry. The K&H is *designed* to handle being run dry (water runs out, container leaks empty or an animal trips on the cord and pulls it from the water, etc). I have pulled the K&H from the water and it shuts off (in a few minutes it is cool to the touch)...put it back in the water and it turns on again (pull it from the water and it is too hot to touch). The submersible aquarium heater also is *supposed* to have a safety feature that will turn off the device if no water is present. I came home one day after having been out of town for a few days to find the bucket with less than 1/2" of water in the bottom. The aquarium heater element was exposed, sizzling and had melted one of the suction cups AND PART OF THE BUCKET. For me, this was just too much, too close of a call, to continue trusting the safety of this device. Yes, I should have been more careful or used a bigger bucket to not allow the bucket to run empty, but this would never have happened with the K&H. I know there are a lot of folks out there using submersible aquarium heaters and have not had any issues with fire...yet. It is Russian Roulette to do so, if you ask me. For the same or slightly more price (I paid $3 less for the aquarium heater I had used for a short time), you can get this K&H de-icer, which was designed SPECIFICALLY for outdoor/farm use. I'd hate for you to lose all your chickens (and maybe your home, too) because you saved a couple dollars.

For those of you who are balking at the 250W (or higher) rating of this device over the 25-100W of an aquarium heater:
Unless you are on a solar-powered setup, it won't matter much. The higher wattage simply means it will take less time for the device to heat the water. For example, it might take 10 minutes for the 250W device to heat the water to X degrees, but it might take 2 hours for the 25W one to do the same thing. Which one uses less electricity? In this case, the 250W device uses less. Also, since the 250W device is not operating as long of a time, it will better protect the internal components from wearing out prematurely...meaning your investment should last longer than with a lower wattage device. This is all hypothetical and of course it would depend upon your exact climate/circumstances to better determine how a particular device would work for you. But if the fire danger doesn't sway you from the aquarium heater, perhaps the reality that it probably is going to use less electricity than you think, will.

Other thoughts: If you are considering this K&H device from Amazon, wait until Autumn to purchase it. At least for the last 3 years, I have noticed that in the Autumn the price drops about $10-15 and a free shipping option becomes available. In summer time, shipping is an extra $10+ and the price is another $10-15 higher.

Notes on the included images: This is my chicken watering winter setup. The Reflectix (aluminized bubble wrap) is unnecessary. I used the bucket setup without it the first winter, which was actually colder than last year. I added it to try to use perhaps a bit less electricity. The brick on top is simply to hold the lid on better, as it is not the correct lid for this bucket and doesn't snap on tight. I suspended the handle of the bucket (the bucket rests on cinder blocks) simply to act as a deterrent to the chickens roosting/pooping on the bucket (it works well for this).

ORIGINAL REVIEW (circa 2013, aquarium heater NO LONGER recommended):
It keeps the water in the bucket thawed, but the nipples would freeze when it got below 12F. The bucket was hung in a fairly well protected from wind spot. Switched to a 50w submersible aquarium heater, problem solved. It does keep the water very warm compared to the K&H deicer, but at least our chickens don't get stuck with no water access.

IMPORTANT NOTE: DO NOT USE SUBMERSIBLE AQUARIUM HEATERS OUTDOORS IN A FARM/BACKYARD CHICKEN SETTING - FIRE HAZARD!!

Perhaps I was lucky on this purchase, this 500 watt deicer has been working great for 8 years! Our winters vary from warm and balmy to below freezing and down to -10' . This product is used on a 100 gallon tank and has never failed! "¦but on my second purchase 2 months ago I bought the 750 watt for a 170 gallon tank and recently it started to malfunction overheating the tank. Contacted the seller, their advise was to clean the heating coil, and to call the manufacturer"¦after not returning my call, the seller then gave me the email address of the manufacturer, after e mailing a copy of the invoice and a photo of the unit with the electric cord cut, my info was forwarded to the warranty dept, a few days later I received a new unit.🎠sadly it seems malfunctions are a common occurrence with most deicers for one reason or another, but in this case, the manufacturer stood behind their warranty and replaced the unit.👩ðŸ»"💻😃