To accomodate C. vulgaris to test conditions, algae cells have been cultured in OECD medium for 4 days before tests. The inoculum was continuously aerated with sterile air and illuminated with magenta (red + blue) LED grow light with the illuminance of 5500 ±800 lx. Before tests, the inoculum was diluted with pure medium until its absorbance of monochromatic light (688 nm) was in the range of 0.05-0.08 at 10 cm path. To obtain the desired range of concentrations, 19 cm 3 portions of diluted inoculum were mixed with 1 cm 3 of the prepared toxicant solution in OECD medium. In the case of control samples, 1 cm 3 of pure OECD medium was added.