What test do you use? Again, it’s Tukey’s HSD! That’s because when you conduct post-hoc tests, you need to adjust your overall alpha to account for the number of tests that you would need to have conducted in order to do the test of interest (here, you would have needed to do ALL pairwise tests in order to do this pairwise test). Tukey’s test is what you would use, since you did not do a complex comparison and you did not plan this comparison in advance.