Not loving that feed, simple reason - if you cut power etc - you risk introducing air... These reactors work in an anoxic (low oxygen) or anaerobic environment, introduction of air (due to say return pump failure / turning it off for maintenance) would harm the bacterial culture.
Low tech fix - mechanical float - similar to RO / top off floats... So if water level drops below a set height it cuts off flow.
Lower tech fix - add another valve as a cutoff for maintenance (if your like me - add a reminder label to the plug / switch for the pump) and prayers go a long way I'm told
