Abstract—The effects of Modified Zarrouk Medium (MZM) with different pH on Spirulina maxima culture were determined using five parameters: the growth rate, lag phase duration, nutrients (protein, carbohydrate and lipid), pigments (chlorophyll-a, betacarotene and phycocyanin), and morphology of the algae. The experiment was divided into 4 treatments. All treatment contained the same MZM; however, different initial pH of 9, 9.5, 10 and 10.5 were applied to the experimental treatment I, II, III and IV, respectively. The parameters of these treatments were compared to those of the positive control (the Zarrouk medium pH 9). The results showed that the algae grown in media treatment I could reduce the duration of lag phase and gave the highest specific growth rate (4.12 ± 0.005 g/l), while the algae grown in media treatment IV provided the lowest specific growth rate (1.09 ± 0.006 g/l). Regarding nutrients, the algae grown in media treatment I provided highest protein content of 71.0±0.06 % and the algae grown in media treatment III provided the highest carbohydrate content of 17.07±0.02 %. It was found that algae grown in media treatment I yielded the best in pigment contents, which were the chlorophyll-a (15.2±0.16 mg/g), beta-carotene (3.16±0.32 mg/g) and phycocyanin (46.37±0.20 mg/g). The Morphological studies of algae using microscope SEM and TEM revealed that most trichome of algae grown in media treatment III and group IV were changed from helicoidal to straight.