Science Buddies: "Ask an Expert"

Hello,

I’m doing a science project on how turbidity and suspended solids affect the growth of chlorella vulgaris. Essentially, i’m planning to have multiple containers with algae cultures, with varying amount of sediment and a water flow machine that stimulates movement. The project pretty much seeks to find out the effects of erosion and suspended solids on the growth of algae.

Would a pH meter be an accurate way of assessing the growth the algae? I’m not sure if there are any alternatives, that are necessarily affordable or easy for me to get my hands on. (Secchi stick won’t work considering the vision of the culture will be clouded by the dirt)

Furthermore, how exactly would I gauge the growth? I’ve done a bit of research and chlorella vulgaris seems to grow the best at around 7.0 pH. Would a lower or higher pH signify less or more growth?

Thanks for any answers and clarifications.

Hi there,

Thanks for your question!

To monitor the growth of Chlorella vulgaris, it is best to use optical density (OD), which can be accomplished using a spectrophotometer. Since the algae will most likely have an optimal pH for growth (i.e., between 6.5 and 7), a more acidic or basic pH would not be a good indicator of growth. However, it would be good to use pH to ensure that your growth conditions are optimal for C. vulgaris.

This paper discusses using OD as a measurement of algal growth: https://www.ncbi.nlm.nih.gov/pmc/articl ... po=13.6364. You can find other manuscripts that use OD to measure algal growth in Google scholar or PubMed.

Hope this helps!

--Brandi