That's what I was thinking. 13W CFL has roughly 900 lumens. That alone may be sufficient for plants like vallisneria and sagittaria, but the light will not be spread evenly, leaving the corners too dark. The light output of CFL will also vary depending on reflector used (if any). That's why I like led strips with simple manual dimmer, you have full control over the light output and can be changed according to you current needs. Downside is the soldering, wiring and overall hustle with proper installation in plastic top. Especially with many low output strips next to each other. Effect of heat and humidity also have to be considered under this closed top.