Growing Chaeto

[Reef Pilot]

I have some Chaeto in my refugium, but it is not doing too well, not dying, just not growing. I have some Caulerpa Prolifera in the same tank, and it is growing, although a little stringy and small leaves.

Not sure if it is my lighting, or lack of nutrients. I have two T12's, one daylight, and the other 50/50 daylight/actinic, so looks pretty bright to me. The nitrates and phosphates are near zero, with my tests. I have a big skimmer in my sump, and also use phosphate remover chips in a canister.

The Chaeto is on the bottom, though, in a corner. Should it be higher, closer to the light? Water flow is lower in that corner, too.