On a 29 biocube running since 2014, with media and refugium basket in back, I started with the JBJ nanoglo mentioned. It had 4 bright white LEDs and I had to mount it on the wall behind the tank because when I mounted it directly on the glass, the chaeto closest to it would bleach. I also had to shield the sides to reduce light scatter in the room at night. Last year it stopped working, I replaced it with the IM 9w chaetomax mentioned, and stuck it to the back glass. The chaeto growth with this light is much better with no bleaching whatsoever mounted directly on the back glass. Didn’t have to shield and there is a really nice pink glow coming from behind the tank at night. The red LEDs really do make a difference.
IMHO, worth $70. I used to run a bag of chemipure and purigen in the media basket. I pulled them both and keep just a filter pad up top. The chaeto is keeping nutrients in check beautifully along with a aquatic sealife skimmer in chamber 1. Look at this chaeto brick ready to be cut in half lengthwise.