What's wrong with the fan?
What is this 650, 400something nm
what is best? does it really matter? some lights are coming with sayyy a 6000K lamp and a 650nm lamp.....?? what?
That's referring to the light wavelength in nanometers. The pigments in a plant absorb light at specific peaks in the wavelength. Photosynthesis is usually the most effective at two peaks, one around 430nm and one around 680nm (because Chlorophyll a absorbs light the best at those wavelengths). Other plants (and algae) will vary but not in your situation.
Those two wavelengths you mentioned would be fine. If you want to really take advantage of wavelengths, mix a few different kinds of bulbs.
In case you're curious, these "peaks" translate to violet-blue and orange-red light. They (the plants you have) absorb green and yellow light very poorly which is why they're green--the green light is getting reflected off instead of absorbed
Most plants don't seem to grow well with actinic bulbs alone (even though blue light is one of the peaks, they make better use of the other peak) and there is some evidence suggesting that actinics cause plants to focus on growing upward (they "think" that they're being shaded and need to reach towards the sun), leading to more straggly (not lush and bushy) plants. Many algae species also make better use of the blue light than plants do which could technically lead to algae growth (not usually an issue in mature, well-maintained tanks but I figured I'd throw it out there). The only reason to use actinic bulbs is to get a more blue color or as evening "moonlight" type lighting. There's no problem with doing that, many people do. But if you don't like the "blue" look, just switch out the bulbs for more daylight bulbs
As for the numbers like 6000K and 10000K...all you really need to know is that it's referring more to what the bulbs will look like. Higher numbers closer to 10000K will produce a crisp white light, getting more blue as the number gets higher (12000K is really blue!). Lower numbers like 6000K will be more yellow-ish, looking more like sunlight. And of course the actinics are deep blue or purple.
Hopefully that helps a bit. I'm definitely far from being an expert on lighting, though, so if anyone reading this can chime in, great!