This paper presents an experimental study to determine the effects of pH level, temperature of the tank, and temperature of the grow bed on the length of the Nile Tilapia and plant height of the Romaine Lettuce using the automated aquaponics system and to recommend optimal combination of identified factors to maximize their growth. A 2³ Factorial Design with two replicates for sixteen runs was used to perform the experiment and the results were processed using the Minitab software.  Measurement on the length of both the Nile tilapia and Romaine lettuce was done once a week.  The experiment lasted for 112 days.  The results indicated that the pH level, temperature in the fish tank, and temperature in the grow bed have great impact on both the growth in length of the Nile tilapia and Romaine lettuce.  It was also found out that the two-way interaction between the temperature in fish tank and temperature in grow bed significantly impact the growth of Nile tilapia and Romaine lettuce, respectively.  Using Tukey’s test, it was also found out that the higher-level values of the pH level, temperature in fish tank, and temperature in grow bed showed significance when compared to other levels for a one factor, two-way interaction, and three-way interaction.  Moreover, the optimal values of the pH level, temperature in fish tank, and temperature in grow bed for both the Nile tilapia and Romaine lettuce were (7.0 pH, 30°C, 27°C), (7.0 pH, 27°C, 27°C), and (7.0 pH, 30°C, 24°C).