Glad to hear that you caught it in time Mindy. Seeing that we are experiencing a bit of a heatwave at the moment everything should be ok, luckily it didn't happen in winter as the tank could have got quite cold. You should be ok though, just keep an eye on them for the next few days.
TTA's advice is sound, two smaller heaters is a good precaution to take as it is unlikely that both will fail at the same time. Also if one of them fails in the on position it will take longer to overheat the tank, luckily most failures happen in the off position. I have external digital themometers with an audible alarm function that would alert me if the max/min temperatures I programmed were exceeded. You can pick these up for about £15.
All my zebra tanks are heated with thermo filters, heater element in the bottom of the canister, and I have found them to be very reliable. My oldest one has been running in various community tanks for about seven years now. I do have a few tanks that are heated with conventional heater stats. In my experience the most reliable brand of heater I have used to date are made by Eheim Ebo-Jager, a bit pricey but they are very good quality. The best feature being the overheat safety shut off, the shatter proof glass comes in handy too. Heaters with an external thermostat, as commonly used by marine keepers, are also very reliable and are able to hold tempearures more accurately. The titanium range of heaters seem to be popular with the marine folk, I quite like the look of these and have heard a lot of good things about them. However I can't seem to find them in the UK though. As an alternative aquaone have a similar range but made out of stainless steel, I'm not sure about the reliability of these though as they are fairly new on the market I believe.
I strongly advise investing in good quality heaters.
Regards.
Adam
PS Also don't forget those heater guards, these are nice and cheap.
