"Chaetomorpha Algae removes both phosphates and nitrates from the water. To increase the amount of nutrients this algae exports, use moderate to high lighting and keep it in an area of high water flow. It should ideally be tumbled in an algae filter."
For sure an energy saver would be fine for most under the tank Chaeto refugiums. Two bulbs would be even better. Try to put a simple DIY reflector around the bulbs to channel the light to where it need to be, and not on all the other equipment in the sump area. That is just wasted light and will cause algae to grow inside skimmer chambers and in clear pipes etc. etc. Another tip is to add flow in the tank in such a way as to make the Chaeto ball tumble constantly. Slow tumbling is fine. In this way light is able to get to the whole mass of Chaeto rather than just the top. The result is faster growth and fast nutrient assimilation. (up take) I have just finished installing a largish Chaeto Refugium. The fuge is a 1000 liters square tank and has a 250W 10K bulb in a Luminarc III reflector. It has 4 SEIO 1100’s. Two at the top and two at the bottom on opposite sides in order to get the flow to go “head of heals” I plan to have a massive ball in there!!
andrew i have my chaeto in my dsb but there no movement there as ive used "your" design in the sump and water flows gently over the dsb ... i have a 3foot biolux (plant tube used in freshwater tanks). the growth of the chaeto has been minimum but the amt of liitle tubes worms growing out the chaeto has been great !!!
Cheato has many advantages, reduces nutriet level naturally, wont go sexual as many other weeds do, easy to keep the lattice type pattern that it forms is a perfect breeding area for all the little critters we are trying to breed in our refugiums.