Heating a 2.5 gal tank?

[DiverBettaDoll]

Hi guys,
I'm getting my first tank set up, and while my betta is happy with his temperature now, I want to buy a heater soon. However, there's a lot of contradicting information out there about which heaters are too hot or not hot enough.
So far I'm deciding between the Elite Submersible Present Heater 25-watt Mini from Hagen, and the Hydor Slim 7.5 watt heater for Betta Bowls, but I feel like the Hagen might be too hot and Hydor not hot enough.
Help?

[ngrubich]

I use the Marina 10W (C10) heater in my betta's 2.5 gallon. It's preset to stay around 76-78, but with mine, the water stays right around 78-79 depending on how warm the house is.

http://www.petsmart.com/product/inde...ductId=4134008

[aokashi]

is the hagen one adjustable? if it is, id say to go for that one.

[ngrubich]

If I remember correctly, the Hagen on is preset. I don't think there are too many adjustable heaters under 25W. I know of a few, but can't remember the name of the brand.