Statistical analyses were performed with IBM SPSS 19.0. In the
case of TN removal and TP uptake by
floating algae, data were
distributed normally and variances were equal, so an ANOVA was
performed. In cases of significant differences between treatments,
the ANOVA was followed by post hoc testing using Tukey's HSD
test. In all other cases, a non-parametric Kruskal–Wallis test for
multiple comparisons was applied to test for differences between
treatments because the data were not distributed normally and/or
homogeneity of variance was lacking. When significant differences
between treatments were present, Mann–Whitney U tests were
performed. A Bonferroni correction was applied to overcome
inflated Type I errors, reducing the level of significance to 0.05/
3 = 0.017. During all other statistical tests, the level of significance
was held at 0.05.