I have 5 flasks.
Flask 1 has only water (50 ml).
Flask 2 has salt water (50 ml) at a certain concentration (say 10%). I call it dilution factor 1x.
For flask 3, I create a 2x dilution solution by mixing 10% salt solution with water in 1:1 ratio.
For flask 4, I create a 4x dilution by mixing 10% salt solution with water in 1:3 ratio.
For flask 5, I create a 8x dilution by mixing 10% salt solution with water in 1:7 ratio.
I add bacteria in each flask and calculate bacterial growth* after a day. I want to know if there is a significant difference in bacterial growth between the different flasks (i.e. dilution factors). Can I use one-way ANOVA for this, and then use Tukey's test to do pairwise comparisons? My only concern is whether the variable I am testing here (dilution factor) be considered categorical (a requirement for ANOVA) and if the different levels of this variable can be thought to be independent of each other (another requirement?). All experiments were done in triplicates.
*bacterial growth is quantified by measuring the absorbance of the bacterial solution at a wavelength, which is a function of how many bacteria are in the solution.