[mnemenoi]

A small LED (like a SPEC 2) or CFL screw in and clip on lamp should be more then enough as all your plants are low light and in such a shallow tank I'd worry about overheating the water. Honestly I think the heater is likely not necessary unless it is set on 74. Usually your house temp will be fine unless it goes way low (into the mid 60's). Most shrimp (discounting Sulawesi species) like a lower temp in their tanks.