It looks like they are almost ripe, I just wanted to get some opinions about when I should harvest, one cola looks like about 45% of the pistils have shriveled but the rest are mostly still white and new pistils are still showing every day on most.
Those plants are very hungry. You need to be feeding bloom specific nutes now. Like Biobizz Bloom. Also, you didn't mix anything into the soil to act as a buffer, so you are probably experiencing some pH problems as well.
More light would help as well. 300w of CFL would do nicely. Are you in SA? If so, have a look at GT Hydro. They sell 150w CFL bulbs for R400, which is quite a good price.