Like many keen Fish Keepers, I used to have the traditional tank set up. It consisted of an External Filter and an Internal Heater which was attached inside the back of the Aquarium by a couple of suckers. As long as the flow of water was good across the heater, the temperature was distributed evenly with no cold or hot spots.
This was fine until I purchased a Bristlenose Catfish. He often would rest on the heater or get dangerously close to the heater element itself. With the species habit of continuously sucking everything with a microbe of algae on, I could see this was an accident waiting to happen. I considered a plastic guard to clip over the heater, but this looked ugly and further took up much needed space. So what was the answer?
Then, when Googling, I found the answer! The Hydor External Heater !!!
I bought this almost straight away after viewing. Put simply.. it is Brilliant. Controlled by internal electronic circuitry, the heater slots into the return piping of the External Filter. It was very easy to install, with just a sharp knife needed to cut the filter piping. To work properly, the device has to be in an upright position.
The benefits I saw were immediate. Firstly, the Aquarium was now at a more even and universally stable temperature. This was because all water now entering the aquarium was at the correct temperature and didn't have to be heated and distributed uneconomically from one stagnant place.
Second, the amount of extra space created by removing the Internal Heater was greater than I had imagined. I hadn't noticed before, but fish generally would give the old Internal heater a wide berth as not to burn themselves. With this threat now gone, the area and immediate surrounding area were converted to free swimming space.. much healthier for the fish.
Thirdly, my Britlenose was now free to go wherever he wanted without the unknown danger of being suddenly frazzled!
If you are experiencing similar problems to those that I had or you simply just want to free up some more room in your Aquarium, I would whole heartedly recommend the Hydor External Heaters. The model I have is a Hydor 200 which are suitable for tanks from 100 to 200 litres (26 - 53 Gallons). I paid just over £30 and have it connected to a Fluval 105 External Filter. A great bargain! Also there is a version avaliable for larger tanks called the Hydor 300.
I have now had the heater in place for 6 months and it has proven extremely reliable.