[Aside]

I'm setting up a nano tank and I need a heater suggestion. I'm a little low on funds so I'd like to find a relatively inexpensive heater that I can trust to keep my tank at around 80 degrees. The tank is for a betta and possibly a couple of ghost shrimp. The heater I have now is really unreliable. The temperature is swinging back and forth from 68 to 84 degrees. It got up to 90 at one point before I unplugged it. I don't want to kill my fish.

I should probably mention that the tank is 2.5 gallons but with substrate is really about 2 gallons of water.

 

[sp33drhno]

I've had good luck with hydor theo and eheim jager heaters. The hydor in my 55 is five years old and still working like new.

 

[Beer]

Some people were trashing the Deep Bule heaters for a while, but I've had one in my girlfriend's tank for the past year. It does get unplugged during the warmer months. The Heat Stik is what we have been running. It fits nicely in the filter and keeps a 7 gallon bow at a stable temperature. And by keeping it in the filter there are no worries about uneven heating, or having to see the heater in the tank. You can't adjust the temperature, but I believe the set point is between 78-80*. I think it always held 78* for us.
I believe one is for tanks up to 5 gallons and there is one for tanks up to 12 gallons. You should be able to get them for under $15. Don't get the one for Beta tanks. That one is undersized for most applications and is only rated to keep the temp 4* above ambient, which means it isn't calibrated to maintain a specific temperature and will swing all over the place and lead to the issues you are having now. The are probably designed for tanks smaller then a gallon.
Just make sure you unplug it if you are doing a water change and shutting down the filter (if you put it there). It is a glass heater, so if you leave it plugged in and it gets exposed to the air, it will shatter when it gets re-submerged.

 

[Aside]

I'm going back to the pet store soon so I will definitely check for these otherwise I'll order one online.

I like the idea of an adjustable heater because I feel safer, but how much is that really worth. The price tag of the deep blue is very attractive to me but I want to make sure to keep my fish safe.

 

[Beer]

I'm not really a fan of non adjustable heaters myself, they are usually warmer than what I like to keep my tanks at, but the deep Blue has kept the 7 gallon bow at a pretty stable temperature through the winter months.
And it's pretty difficult to complain about the price.