ISTA I-H616 500W Inline External Heater

Great heater. I was a little apprehensive to use it since I had not known this brand and the few reviews about boiling a tank but those were simply user error.This 500w heater keeps my 55 gallon tank within 1 degree and draws exactly 500w when running and only a few watts while monitoring.As a warning to any new aquarium keeper ALWAYS USE A DEDICATED HEATER CONTROLLER ALONG WITH ANY HEATER! If you cook your fish due to a failed heater, it is your fault for not adding a redundancy shut down option. I suggest the inkbird thermostat heater control for around $35.00. great price for peice of mind.

I was happy with this external aquarium heater. It kept the temperature fairly stable in my 125 gallon tank. Yesterday I realized the tank was cold and the heater temp display said HI. So, I shut it off and put in a couple of immersion heaters temporarily. Today, I was hoping that a good cleaning would solve the issue, but it didn't. So I decided to open it. As you can see from the pictures, some water went inside, the insulation around the heating element didn't work well when wet. You can see the burnt/melted plastic parts and corroded power connection. The reason it failed was one of the temp sensors is open circuit. This is meant to work right outside the tank, attached to a water hose. It's natural that there will be water outside the housing, but that water is supposed to stay outside. All they had to do was to make the case water-tight either by using an o-ring around the case opening, or seal the case shut completely. One can get an electric shock with a product like that. They saved a dollar at best, and the product is dangerous because of it. Unless you plan on using it in a dry environment (ha ha) think twice before you buy.

I bought the 500w heater for my 90 gallon planted tank. So far it works perfectly controlling the temperature, even during a bout of Ich when I had to increase the temperature to 31 degrees Celsius (87.8 Fahrenheit) to kill the parasite in my tank (Ich must have come in on some plant material as I haven't added fish in months).Many complaints about hoses not fitting, but I used the 16/22mm hose as stated in the product description (by Eheim) and it fit perfectly. Warm the hose in some hot water to make it more workable over the fitting. The supplied hose clamping nuts can be removed if you use a different size hose, just add hose clamps.Would be nice if this product had a decimal accuracy, now it's just even degrees Celsius which gives a 1.8 degree Fahrenheit jump for every degree Celsius. If you are trying to keep a specific Fahrenheit temperature, you won't be able to do so without a decimal accuracy on the temperature setting. I printed a small conversion chart on a label maker for common temperatures.Unit does make an audible click when it turns on. Not an issue for me, but might be for some. Unit will fluctuate one degree until it turns on. My tank temperature still remains stable, but it's a 90 gallon tank. Smaller tanks may fluctuate.Unit will remember the set temperature in the event the power gets shut off. Also very easy to set and adjust the temperature. Digital display is nice.I only gave a four star review as I'm unsure of product reliability or longevity.

Was running a huge marineland submersed heater and my tank would dip a few degrees at night (when house furnace was turned DOWN), bought this so the temp would hold rock steady day and night and so i could have less equipment inside the tank. Easy install, I did use stainless worm-drive style hose clamps and threw the supplied plastic nut things away - heated my pump hose in hot water and slid it over the nipple and secured with clamp, easy. Set this to 25 Celsius and my water temp holds exactly 77.2 F day and night with never a dip or spike... SUPER pleased!

I did research before I selected this. I read all the reviews and was hoping to receive a flawless product as some people claim faulty ones. I did read the tube size issues and the clamp issues that people reported, so I prepared myself.I have a Marineland C series canister filter wich come with very thick tubing. The picture of this in line heater showed two sizes for tube connections so I figured one would work. As others have suggested, I purchased a clamp kit with it. I measuerd all my tubing out and connected them with ease and clamped them as shown in my photo. After getting everything ready I nervously got the filter pump started crossing my fingers for no leaks...SUCCESS! Now for the heater itself...I set it to 25 degreess Celsius to give my tropical tank a nice 77 degree Fahrenheit living environment. I also have a floating thermomiter and a digital thermometer that I put in to make sure it is still accurate.I watched my tubing connectiones carefully for about 30 minutes and then every hour for the rest of my day, each time looking at the temp and comparing. I was very surprised to see that the in tank floating thermometer and new heather were EXACTLY the same, 77 degrees. My digital only went to a 76.3 and 77.4...not once dropping or raising a full degree all day!I also read that some had water flow issues, but my water flows through this with the same pressure (eyeballing not by technical measurement) very good water current in my 40 gallon tank.I will give an update after long term use or if an issue arises.One year update:Never had a single issue with this running 24/7 (minus water changes) recommended to everyone.