Low flow just means it shut down due to the pump being off. Wont hurt one thing, thats the way its designed. If the pumps on, it will make chlorine. i run my pump 15 hours a day with the SWG set at 15%. Keeps my FC ~5-6 ppm, even in full sun. My CYA is about 50 ppm. Now, if i ran the pump less, i'd have to increase the "on' time of the SWG and maybe increase the CYA. But, im not concerend about power usage. Id rather run the pump longer and keep the SWG on a lower percentage than risk not turning the water over enough and making a near constant low level of chlorine.