Cultivation of gut weed, Ulva intestinalis seedling in 1.2x2.5 m2 cement tanks under different medium recipes was aimed to get competent management of the outdoor algal biomass. Three medium recipes 1) urea, 2) ammonium nitrate and ammonium hydrogen phosphate, and 3) Modified Gillard’s Medium were put weekly to the pond. The initial seedling was used 5 g/m2. After algae 2 weeks of the cultivation, Modified Gillard’s Medium provided an increased weight of 1395.39% 1with a growth rate of 38.64±15.53% day-1, followed by ammonium nitrate with ammonium hydrogen phosphate weighing up 1104.89 % and growth rate of average specific percentage of 35.56±15.83 % day-1while urea fertilizer showed lowest biomass of 66.51% and an growth rate of 7.28±9.58 % day-1. The amount of chlorophyll a, chlorophyll b and carotene in the alga among in three recipes showed no significantly different. The cultivation of Ulva intestinalis should be fed with ammonium nitrate and ammonium hydrogen phosphate for economize cost.