Chaetomorpha linum or C. crassa
Picture taken September 2001, Nikon CoolPix 950 digital camera, no flash

This is by far the best macro algae I have found for a refugium for nutrient exporting. First off it is not a Caulerpa spp. so it does not go sexual and turn into a pile of mush. It is an rapid grower and grows in a very dense cluster like a ball of string.

Another excellent reason to use this species of macro algae is that it lacks holdfasts which are the root like structures in Caulerpa that make it such a pain to remove. Chaetomorpha has no means of grasping onto the substrate other than its curls getting hooked on something.

Chaetomorpha linum or C. crassa
Picture taken September 2001, Nikon CoolPix 950 digital camera, no flash

Here is a macro shot of the algae in which you can just about see the cell walls within it. The growth form of this macro algae seems to be of a single strand. I've never seen a intersection or branch in the structure. If cut in half the new ends start growing.

Chaetomorpha linum or C. crassa
Picture taken September 2001, Nikon CoolPix 950 digital camera, 10x and 7x Tiffen Closeup

This image is about 17x optical zoom. Now you can clearly see the cells within each strand.

All though I mainly grow this macro algae for exporting nutrients, I do treat my tangs to a clump from time to time. All of them enjoy it.

Chaetomorpha Harvesting
Picture taken June 2002, Nikon CoolPix 950 digital camera, no flash

This is about the typical amount I remove every few weeks as part of nutrient export and to make room for more Chaetomorpha to grow.  A standard US ruler (inches) is shown for scale.