scorpio

when it comes to growing plants in a tank what is more important, light wattage or kelvin rating ?

mathas

Between the two, I feel wattage is the more important factor.

If Kelvin ratings were somehow accurately enforced across the lighting industry, it might be a different story, but currently one 5000K bulb may emit very different light than a 5000K bulb by another manufacturer. In my opinion, Kelvin ratings are good for giving you a general impression of how things will look in your tank, but don't give enough information to determine how suitable they are for plant growth based on that factor alone.

GreenMan13

Wattage easily but I don't understand the importance of this question as wattage and color temp are independent.

You need the full spectrum to grow plants. Every color temp from 2,000K to 20,000K has the full spectrum so they will all work. If you did go with a 20,000K bulb you would need a lot of wattage to get enough of that full spectrum though. If you go with a 6500K the spectrum is close to what the sun gives off so it will need the least amount of wattage to grow the plants. On the other hand if you don't have much wattage at all it doesn't matter what color it is as it will not grow the plants no matter what.