the 2n2222 transistor gets very hot very quickly.
So since this is too much current for the npn's can I use a TIP120 Power Darlington Transistor from adafruit for the job?
with a 220 ohm it still get too hot to touch very quickly.
... with a heatsink (or to put it in the tank).
All you need then is say a regular 19v laptop power supply for about $5 and you're golden.