hey folks, just wondering if those of you with a thermo filter from oase (filtosmart or biomaster) have heard a period weird noise from the filter? I’ve determined this is the heater but not sure if it’s a sign it’s bad or not. Both my biomaster and filtosmart do it. I have a sound clip somewhere of the noise which I will add here later. It’s a sort of metallic scraping sound? My cabinet is open backed so that doesn’t help!