Time variability of the magnetic field and line activity indicators of FK Aqr. First two plots from top to bottom show the variability of the longitudinal magnetic fields B_l of the two components of the system in the period 3–16 September 2014 (where (p) and (s) stand for the primary and secondary, respectively). Observations are phased and the rotational cycles are denoted in black, red, green, and dark blue colours corresponding to the first, second, third, and fourth cycles. The last three plots show the variability of the equivalent widths of the spectral lines, given in Å. All error bars are plotted, but some of them are within the symbols.