Just got the woarm white Leds and attached them to the reactor. Put them on a dimmer so it wasn't too bright for the chaeto. Have it just above the lowest setting so it doesn't bleach the chaeto.

http://i12.photobucket.com/albums/a2...pscziqiz7x.jpg

Looks good.

Any updates on how this worked?

Not very well. Got hair algae growing on the chaeto. Had to keep rinsing out the chaeto and putting it back with every water change. Also trapped quite a bit of detritus in the reactor Gave up and went with biopellets. Way easier to maintain and and having better success with it. Key is to go slooowwww and start with 25% of what the manufacturer recommends

Curious if the chaeto was actually growing or just the hair algae, did it make any difference in your tank?

Just the hair algae :(. I didn't notice any growth in the chaeto. In fact it was getting losing its colour. I'm not sure if it was because the lights were too bright or if I didn't have enough flow through the reactor. I think it may have been the latter.
I may try this again a bit later on a separate frag tank I am planning on setting up. I didn't want to mess too much with the display tank. I didn't want to tinker with it so I switched over to BPs that I had used with success before.
I am sure this approach could work if done correctly though. Others have had success using the non-pac bellum reactors on other forums that I have read. Heck people have had success growing chaeto in their aquaclear filter (which is why I think it may have been flow).

Thanks for the reply. I will give it a try and report back.

Other than aesthetics does it really matter if there's hair algae in the reactor? As long as it's confined there & not in your display I'd be inclined to let it be. Probably more efficient at taking up nutrients than chaeto.

Maybe it's the photo but those look to be very dim lights, wrong colour and way too few. You prob know this but LEDs are single wavelength and warm white is not the best for plant growth. I've seen a few of these and the successful LED ones tend to use red/blue mix "3-1" and at least double the lights and turn them up some. Easier to adjust turning down than up because it's easy to know if too much light is the problem.. If this was T5 not LEDs then warm white may be fine because they span a larger wave than using LEDs.