It is more than sufficient light, potentially too much for a managable system. You can grow most plants with half that lighting in T5 with reflectors as George is always saying.
Does your lighting system allow you to turn two sets of light off in case you need to? Either that or can you raise and lower it above the tank.
Watts/galllon is a very rough and ready rule and does not hold so well with larger tanks. There used to be an on line calculator which compared many amano tanks. I think it was fitchfamily. com, but doesnt seem to be there now. Basically larger tanks need less watts/per gallon.
PAR is a better measure, but not many people have access to a PAR meter.
Still basic answer the lighting system is more than enough.