Normal cellular metabolism and function require that blood pH be maintained within narrow limits, 7.35-7.45. Even mild excursion outside this range has deleterious effect, and pH of less than 6.8 or greater than 7.8 is considered – according to medical and physiology texts – incompatible with life. -Source
Algae pH. According to Healthfully, algae thrives in water with high pH levels between 7 and 9. For most algae growth, an optimum pH is between 8.2 and 8.7. A pH level that is neutral or lower can help decrease the growth of algae. -Source
Human vs. Prototheca
The Prototheca species of algae has been found to colonize human skin, fingernails, the respiratory tract, and digestive system.
The genus Prototheca consists of achlorophyllic algae that are ubiquitous in the environment and animal intestines. Although human infection by Prototheca is considered rare, an increase in infections has been noted among immunosuppressed patients, those on corticosteroid treatment, or both. Moreover, the first human outbreak of protothecal algaemia and sepsis was recently reported in a tertiary care chemotherapy oncology unit in 2018.
This organism has forfeited its photosynthetic ability and switched to parasitism.