Chaeto Growth

[Delphinus]

I think the problem is that chaeto tends to be so densely packed in on itself that it is essentially self-shading. So the top surface is probably growing whereas the lower parts probably aren't. Whereas under a halide, the whole ball sort of glows green and thus more of it can grow.

Such is my theory anyhow ... I could be wrong. Maybe if it was in a shallow vessel so it couldn't be tall, ie. only a few inches of water, one could get away with less lighting ... I dunno. <shrug>