Good thernostatic heater for nano tanks

[lectraplayer]

Right now, I have a nano tank set up with a guppy, 2 otto cats, and 5 tetras, and a plant (but I forgot what kind of plant it is) and would like recommendations to stabilize the temperature in the low 70's F. Tank is about 1.5 gallons or so. Right now I have a 10 watt submersible thermostatic (not adjustable) heater that holds it around 74 deg. F and a 7 watt (non thermostatic) "card" heater set aside which seems to push the temps up into the 90's F. Lost two platys to the card heater. Seems like most nano heaters are not thermostatic and most that are claim to be set to 78 deg. F. Is there a heater for nano tanks that either can be adjusted or regulates around 70 deg. F?

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