The total ammonia concentration fluctuated highly between 0.1 and 0.4 mg·L− 1 in system F (0.25 ± 0.14 mg·L− 1 and 0.16 ± 0.09 mg·L− 1 respectively for the treatments FC and FL), while it was very stable below 0.1 mg·L− 1 in system R (0.06 ± 0.04 mg·L− 1 and 0.04 ± 0.02 mg·L− 1 respectively for the treatments RC and RL).