Algae Barn, Sea Lettuce – Ulva sp. is commonly found on shallow, rocky reefs worldwide. This delicate green algae prefers fertile, brightly lit waters. Thus, it can quickly reduce concentrations of dissolved nutrients such as nitrate and phosphate in marine aquaria. At AlgaeBarn we treat, quarantine and inspect all of our CleanMacro Live macroalgae such as Clean Sea Lettuce.