Been using this method for about 3 yrs. I like that it acts like a natural filter pad, and the thicker it gets the more detrius and particles it holds. Then, it gets full of all kinds of shrimp and zooplankton. I place it on the back half(50%) end of the refugium against the overflow baffle. That way a large % of the water exiting the refugium has to go through it. I have not experimented with 2 Chaetopads covering all(100%) of refugium area but it would probably work more efficiently, in having all refugium water flow going through the Chaetopads. I haven't tried. With 1,growth is fast. I use 6500k PC bulb 24 hrs on, and I harvest the Chaeto about every 1 1/2 -2 months with a newly set up tank. As the display tank matures, the chaeto growth seems to slow. I haven't changed the core Chaeto (within the panels) since I started it. I think I'm gonna open and place fresh Chaeto inside soon cause I am getting some nuissance algaes attached to the chaeto, mostly red bubble algae. Hope you all benefit from this idea! Thanks.