Yes it is 18,000k. How long have you had that light over the tank? I was thinking it would be a good combination with the Life-glo lamp for my 29 low light tank.Well what my main goal is to turn my 20 gallon tank into a jungle, more like an aquascaped jungle. lol. If anything replace the 24" T8 Power-Glo Fluorescent bulb (ie. i think it is 18,000k) .
Oh, and BTW the ratings for bulbs are not consistent. Thus you can't go by the kelvin ratings to get specific spectrums. Some of the lights show on the side the colors the bulbs give off. I believe the Power-glo has a lot of red spectrum and a little blue which help plants be more showy. Here more info on the spectrums
I was just thinking that I may have cause more confusion. My point is that the color spectrum is more important than the wattage. An example of this is Trallen44 tank here.
He only has 1 Zoo Med ocean sun 10,000K T8 32 watt 48" bulb
That is a good product. I accidentally bought it in a rush thinking it was Seachem excel. Plants have been doing good since I started using it. The gh of the water, type of plants and light will determine how many ferts you need to add. If you want to add more it may be cheaper in the long run to buy Plant Nutrient from Big Als. I would wait until you get the diy Co2 up. For I have seen some tanks that use no ferts with the diy Co2 and have great growth. Another good line of plant food is Bright well aquatics which was Kent at 1 time. You just got to weigh in the cost of getting the item.But at the moment i only dose my tank with Flourish:Comprehensive, and nothing else.