how much light in a 55 gallon tank

Here is a picture of my 55gal, As you can see the plants are growing out of control (I really need to do a good trimming). This tank only has a double strip light on it 80w total about 1.4wpg.

It really depends on how much time, effort and money you want to put into the tank.
The tank that tai95 describes is considered a low light tank, but can grow quite a few varieties of low light plants.
If you want more variety in plants you could step up to a compact fluorescent and get a nice 2X55 watt set. Compact fluorescent penetrates water better and gives the hobbiest more options.

Len