I've not used these flourex lights, but I did just take the liberty at contacting Len at lenslights.com. He said each filter added reduces lumens by about 20%. One filter gives you a little more than 9500k. To reach a 12000k color temperature, it would take 2 filters and he said you'd lose about 35-40% intensity.
I wish someone here had real experiences with this light they could share.
aural, I hear what you're saying... but all too many times manufacturers prey on our hobby to charge an arm and a leg for "specialized" equipment. Honestly, there isn't any reason ballasts and bulbs should cost as much as they do. This is why we do things like the "maxi-mod" instead of buying a tunze stream. I think its a great idea to try and come up with alternative light sources. Its been said that these flourex lights will take over HID lights one day. It could very well happen. I've read alot of "growers" have been using these lights with a lot of success. I'd like to hear some reef hobbists experiences with the product.