What wpg is considered high lighting, medium lighting, and so forth? i have a 20 gallon high tank with 60 watts fluorescent, i use the pps pro fertilizing method, with a fermentation co2 kit. i want to buy some really cool plants from an online store, but the best ones require "high lighting" and are "difficult" to care for. So what is the run-down on the lighting? and also, i know this is a lighting forum, but would i need pressurized co2 to keep these "difficult" plants?