Water quality management for aquaculture is very important because water is a living medium for aquaculture organisms. One of the technological products that use microbes to create a better environment by breaking down organic matter is probiotics. This study aims to determine the effects of different probiotic administration times on water quality in white leg shrimp culture at a laboratory scale. Juveniles of white leg shrimp with PL27 size were reared for 45 days and given four treatments with probiotics at different times. The result showed that the administration of probiotics with a short period interval had a significant effect on floc volume, absolute growth, survival rate, concentrations of ammonia, nitrate, and nitrite. Provision of probiotics with a short time span tended to reduce the concentration of ammonia, nitrate and nitrite. The difference in time of giving probiotics to bio-floc media increased the growth of white leg shrimp, improved water quality, and reduced the concentration of ammonia (NH3), nitrate (NO3), and nitrite (NO2).