those skimmers don't look "budget" at all. what do you mean they haven't been working? the pumps that run those skimmers pull air from somewhere, and mix that with water. if the reaction chambers of the skimmers has nothing but water in them, the pumps are most likely not working at all, malfunctioning and need servicing, or the air supply is blocked.
once you figure this problem out you should implement an automatic top off so that the water level is always at a constant.