A study published in May 2009 by the Journal of Bioscience and Bioengineering, examined optimal conditions for the growth of Porphyridium cruentum lipid production. Sung Oh et al. found that 30˚ C was the ideal temperature for the production of lipids by this species of algae; at this temperature (which yielded best results) increases in light intensity resulted in increases in cell growth. Cell concentration reached its maximum concentration (2.1g-dry weight per litre) after 15 days in the 18 hours of light per day treatment. The other light treatment (12 hrs. per day) was capable of supporting the same total cell concentration. This led the authors to conclude that 12 hour photoperiods.
Oh, S., J. Han, Y. Kim, J. Ha, S. Kim, & M. Jeong. 2009. Lipid production in Porphyridium cruentum grown under different culture conditions. Journal of Bioscience and Bioengineering, 108:5, 429-434.