Well if there were lettuce "nudibranch" the bottom line is they do not "eat" any algae, they harpoon it and suck out the chloroplasts (green stuff), regardless of tank habits the way they work won't change. Not saying they won't control algae that gets out of control, but if you have the nutrients in the tank that caused it to start (perhaps improper skimming) then having them won't help much, however if you up your skimming or something after getting an outbreak, or perhaps having a minor nutrient spike, then sure they'll help. Just that in most cases you can trace back the cause of the algae and fix that to fix your algae problem rather than buying some exotic animal to take care of it.