I'm sure you've tried it, but does cycling the power on/off a few times make the sound change at all? Did you pull the pump apart at all? I hear you that you shouldn't have to on a brand-new filter, but I know when I got mine via mail order, there was bio media dust all over the thing. Maybe some of the abrasive dust got into the pump?
I don't recall my tidal 110 being overly quiet when I got it, but I do think it's gotten quieter over time.
I don't recall my tidal 110 being overly quiet when I got it, but I do think it's gotten quieter over time.