Too little or too much light can cause algae blooms. High nutrients and not enough water movement are usually the main culprits.

The 58g tank is 36.5x18.5x21. Your not going to have near enough light if your trying to grow difficult LPS or any SPS. Softies should do ok in your tank though.

I prefer the 14.5/15K lights, but also like the 20K as well.