180l Heavily Planted Shrimp Tank

[Spishkey]

i have a spare rio 180 sitting here so have decided to use it for all my 'spare' plants and throw my quickly increasing colony of cherry shrimp in there.
now as the shrimp are in there i know i'll need a filter but do i need a heater? (room is always warm)
also with it being heavily planted is CO2 needed (id prefer not as i guess that will work out expensive?) i have installed lighting which supposedly promotes healthy plant growth and used a substrate recommended for healthy plant growth too. am i forgeting anything important?

 

[saz326]

do you have any plant food in the substrate? If not bung a coupld of root tabs in by your plants. You can split the tablets up if you want to dose the tank up regularly. The plant roots feed well off these tablets and they promote better growth.

 

[Spishkey]

do root tabs go off? i have some here but they were opened about a year ago?
also any idea how long i should keep the lights on for?