LED is not necessarily "better" than what you have, if this is what you mean here. I'll try to explain this a bit.
Aquatic plants grow by photosynthesis, and photosynthesis is driven by light. Intensity and spectrum both factor in to "light." Light is composed of colour wavelengths (the spectrum). Red and blue light is the most important as these drive photosynthesis. Red is the more important of the two. "White" light is a mix of colours, and manufacturers can vary the wavelengths to provide higher levels in this or that colour. The colour can be indicated by the "Kelvin" rating; lower numbers are warmer because they have more red/yellow and less blue, while higher numbers are cooler because they have more blue and less red/yellow.
The best lighting, according to results from scientifically-controlled tests, is a mix of red, blue and green. This is often termed "daylight" or similar, because it tends to be close to the sun at mid-day, in the range of 5000K to 7000K. Daylight tubes are often around 6500K. I use these on all my single-tube tanks, and on those with two tubes I use one 6500K and one 5000K.
Two of the 15w Bright Day White tubes/bulbs shown in the photo should be sufficient intensity, and probably spectrum too.
LED light has these same issues. I have tried four different fixtures, none were any good at all, and went back to the store. I won't recommend LED because I don't have the experience, but you need good LED plant light to make it work. Most LED is more blue and too little red. The Daylight mix has both (or should). I experimented with more blue and the plants weakened and algae increased, because the red was too little. I would try two Daylight tubes/bulbs and see what happens. It takes a few weeks for plants to adjust to changes, so don't expect to see much change quickly.
Nutrients have to balance the light before plants can fully utilize it. One of the comprehensive fertilizers should fix this aspect.
Byron.
