anyone use these bulbs?

[AJ_77]

Their "Spectral Distrbution" graph on the site doesn't look to match the expected output of a 25K bulb. You want to be spiking more in the blue range... for a "blue" bulb.

Maybe they posted their daylight bulb specs by mistake. A mix of the 2 might give you decent results, as BobI mentions. I've got nothing against PC lighting, as long as your tank isn't too deep.

You haven't said what size/type of tank you're running, and what you want to keep in it. If it's a medium or low-light sort of setup you might be fine with these - if you can fit enough of them over your tank, with good reflectors to make the most of them.