As I was endlessly tinkering under the tank this week and contemplating all the sump changes I could make, I started thinking about another project I'm working on. The other project is a hydroponic setup using fish to add nutrients to the water that the plants will take up. Our refugiums are really the same concept, just without roots as the means of gathering nutrients. It seems to me that the limiting factor for our refugiums is (surface area) exposure to light. In a narrow fuge I can grow more cheato if it tumbles. Without tumbling I need a fuge with more surface area as the deeper cheato will be shaded by the light drenched cheato at the top. In my fuge I run a mix of about every algae I could get my hands on. I regularly mix it up and stir it around. Still though I have the issue of deeper shaded algae not thriving the way the light drenched algae does. A larger fuge (deeper) would do very little, to me it seems, in allowing me to grow more algae. If anything I think that a submerged light would be more beneficial given any space constraints. In order to grow more algae mass I'd need a larger surface area and possibly more light. Maybe measuring fuges in gallons is a pointless endeavor as length and width (plus flow) are likely far more meaningful than depth + flow. Has anyone tried a submerged light? I run about 10% of my volume as fuge and its pretty shallow. I don't find space to be a limiting factor for me but I think the 10% vs 20% vs 5% to be an irrelevant conversation by this theory. It should just come down to flow plus surface area as I understand it. Thoughts?