Originally Posted by Newt
A T5 ballast most likely will not drive a T5HO bulb w/o rewiring - if that's even possible.
On the 6500K bulb you are looking at, I suspect it has a lot of green light in the spectral output. Impossible to tell w/o a spectral output graph. I have always preferred to mix bulbs of different kelvins. Also, the kelvin color temp (CCT) only matters to you and how it makes your tank look. You need to look at the light the bulb outputs in the visible spectrum and see if it has blue light and red light at the proper nanometer to achieve good photosynthesis.
Thanks for the info
Is there a t5HO fixture that would fit a 25 gallon that you could suggest? I really wanted a higher amount of light so that I could grow a wide variety of plants, including something that floats to diffuse light. I dont think 2 14w bulbs would be enough for a 25 gallon, right? That would only give me 28w/25 gallons