Help me with heater wattage

[Fish_lover]

So my betta fish need heaters I already know which one I'm getting for the 3 gallon but i Dont know how many watts I should get for the 2.5 , since it a betta fish it need to get to at least 78 degrees , but not less than 76 degrees

 

[Fish_lover]

I'm getting this one for the 3 gallon

 

[Scottyhorse]

Go with Hydor for little tanks. Very nice heaters. Aqueon is kinda hit and miss for quality on equipment.

You could use a 25 or 50 watt heater.