Make sure you get the food dissolved good before putting in. I think that was caused it. This is message from seller:
Here are some possible causes of this situation: 1.Plant food is not completely melted. 2.The pump rotates abnormally inside, touches the casing causing noise. Based on the above factors, you can: 1. Shake the plant food bottle well to dissolve it completely. 2.Disassemble the pump, clean it and reinstall it, I've attached a picture to help you. If neither of these solutions solves your problem, please get back to me. Best Regards, TILTOP
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