Know the right de-icer to use in your area and for your specific need. Most of the time, the malfunctioning of a de-icer is not due to a faulty internal mechanism. Improper usage is perhaps the most prevalent cause of either a sub par performance or total failure of the de-icer unit. This 500-watt de-icer is perfect for 5 to 25-gallon metal/plastic containers and automatic waterers in Zones 2 and 3 and for 25-gallon applications in Zones 4 and 5. For Zones 6 to 8, the 500-watt de-icer is perfect for 50-gallon waterers. This unit is a plastic-safe cast aluminum submergible de-icer. Meaning, you can use it on metal, plastic, and structural foam tanks without the need for a protective guard. The most common applications for this de-icer unit are on stock tanks, buckets, small animal waterers, and birdbaths. Other de-icer applications include preformed plastic ponds, ponds with liners, and fountains. Cast aluminum de-icers are near indestructible and more cost-efficient but just like other types of de-icers, cast aluminum is also prone to calcium buildup especially in areas with hard water sources. Vinegar and LimeAway were the recommended solutions but diligent limescale and rust removal are almost impossible in the middle of winter. Upgraded 500-watt de-icer provides a solid solution for this problem with a black Teflon (non-stick PTFE) coating film that resists both mineral buildup and corrosion better than other existing de-icer coatings. Experiencing problems with your de-icer unit? Common issues include the unit not turning on and the unit not thawing the water as per its function. For the first issue, the de-icer unit needs to be in cold temperature long enough for its internal thermostat to reset and activate the de-icer's function. To determine if the unit is functioning as it should straight from the box, you need to perform an "air test" (instructions on the user manual).