The growth of microalgae and seaweeds cultured in Hualien deep seawater and Tungkang surface seawater is compared to evaluate the deep seawater for algae aquaculture. Deep seawater (DSW) pumped from Hualien and surface seawater (TSW) pumped from Tungkang coastal water through well, Two free living and three benthic microalgae, and three seaweeds were cultivated in 4 treatments, that are deep seawater and surface seawater with nutrients added or not. Optical density of microalgae and wet weight of seaweeds was measured at the start and end of the culture. Results showed, for all algae, the growth is better when adding the nutrients. For microalgae, the free living ones grew better in TSW, while the benthic ones in DSW. For seaweeds, Gracilaria grew better in TSW, but Sargassum in DSW, however, both seaweeds had more new germinating branches in DSW. Nutrients in deep seawater is not enough to support the algae growing in one week, however, if the seawater is provided in flow through way, the higher nutrients will benefit the growth of the benthic algae and seaweeds.