Refining the Refugium Cover: Blocking More Light, Fighting More Algae

In a previous post, I shared how I tackled the light bleed from my AI Blade Refugium LED by designing and 3D printing a custom cover. It worked well at the time—but after a few weeks of running the tank, I noticed algae beginning to grow in the filter sock section of the sump.

A closer look revealed that a small amount of light was still escaping around the edges of the original cover. While minimal, it was clearly enough to fuel nuisance algae in areas that should remain dark.

So I went back to the drawing board and remixed my original design. This time, I made the cover wider and taller, ensuring it wrapped further around the light source and blocked even more light from spilling into adjacent sump chambers.

The result? A significant reduction in light bleed and an almost immediate slowdown in algae growth near the filter socks. It’s a small refinement, but one that’s made a noticeable difference in sump cleanliness and maintenance.

Sometimes it’s these tiny tweaks to your own DIY designs that bring the biggest improvements in the long run.