As far as lighting the cheato goes, from my personal experience, I had 2 x 55watt 10k compact florecents over my cheato when I started because it was recomended to me. I still had algae, and the cheato growth very slow, and beyond about 1-2" past the surface it just sorta turned clear and decomposed. Not anyway to export nutrients.
So, after a few months of that, I switched to a 6500k spiral setup. I ended up looseing ALL my cheato, and when your tanks only means of filtration and nutrient export is cheato, and you loose it all, its not a good thing.
So, a guy at hydroponics shop recomended I try these homedepot 2700k bulbs, and gave me a pretty detailed explainiation why green algae likes the different color peaks they have. So, I rigged up 6 of them over my fuge, got a couple handfuls of another cheato start, and POOF!!!! The growth is like a small explosion in my fuge. I havent scientifically measured it, but it seems like i produce about 2 packed shoe boxes a week, and if I slack off on harvesting for about a month, it actaully grows clear up and out of the tank by a few inches. It also stays dark green, strong, and healthy clear to the bottom of the fuge rather than just the top 2-3 inches staying healthy.
If you read my post on color temps, its totally possible for any color temp bulb to have the proper wavelegnth peaks. If you took these 2700k bulbs and threw in some phospor that coverts the UV into the 400nM range for example, you could easily turn them into 10k-14k color temp bulbs, and they would still be provideing the proper wavelegnths for algae growth, they would just have some blue thrown in there with it. So, for this reason, I cant judge anyone elses bulb temp recomendations, because they could easily have the 2 phospors in it that the algae wants, along with some other phsopors that make the k value come out anywhere, and it would still grow cheato like a champ. I recomend the homedepot 23watt CF self refected spot light bulbs because I KNOW they have the right peaks in the right places, and you dont have the guess work associated with going with a perticular color temp recomendation which of course has an infinate possible number of wavelegnth peaks that all arive at the same color temp.
Meleevs reef site has a good write up on this. He started with some 6700k daylights, had bad results, but he didnt know it becuase he didnt realize how fast cheato COULD grow. He switched to the 2700k homedepot bulbs, and I belive he quotes that the algae growth "exploded". Later he does a test with some special order 5100k home depot bulbs and they show faster growth than the 2700k by a moderate amount in a back to back test. I think these would be ideal if you want to special order them (9.99 per bulb!!), but for simplicitys sake, the 4 pack for 19.99 of 2700k has been a proven winner for me and many other people whom i helped setup a cheato filled sump for.
