FYI, I bought a Neo-therm about a year ago, because they are super slim and very consistent with the temp fluctuations. I use only on my QT tanks, but have since reconsidered.
There are so many horror story threads on those heaters. I couldn't believe it. Now I'm paranoid about using it. Just wanted to make you guys aware.
Just read the reviews on BulkReefSupply. I suspect in the future they will no longer carry this heater.
Neo-Therm Submersible Heater - Cobalt Aquatics (DISCONTINUED)
Cobalt Neo-Therm heaters are very unique. They have a super thin profile that allows them to fit into tight spaces like on AIO compartments, or sump baffles. With its easy to set and easy to read control system, setting a heater has never been this easy. Easy to set "One Touch" control...www.bulkreefsupply.com
True that there were a number of reported failures with the neo-therms a few years back, but it does appear that they have sorted out the issues and are now pretty reliable heaters.
I strongly recommend having more than one heater. If you go away you have the peace of mind that if a heater does fail you will not come home to a tank full of dead fish. As well it may save on your electricity bills because you can have lower wattage heating your aquarium most of the time. I use a few that total 500w for my 125 in the great white north. I use not too pricy submersables.
I couldn't agree with you more. I keep a second 100w heater in the sump and have it connected to the cooling side of my temperature controller with the min/max temp activation just below the heated side. So in the event the primary fails and stops heating the backup will kick in once the temp drops to the range I have it set to.