Whats The Lowest Fluorescent Wattage For Growing Plants

[bubble87]

im going to get a fluorescent bulb for my fluval edge.whats the lowest wattage i can get to grow plants like crypts,java fern ??

 

[Ps3Steveo]

What size edge is it?

 

[bubble87]

23l

 

[SuperColey1]

15W I would suggest for that size tank