only at night. during the day, it stays in the place i find it in when i wake up the tank. once the lights go out, ill usually wake up and itll be in a different place. it has no problem anchoring, its bubbled out as much as it can be, doesnt look stressed. should i worry?

water tests come back good, the nitrate level is barely detectable. by that, i mean if you hold the water up to the light, you barely see a pink hue in it.

today is water change day, so im hoping itll bring that back down to 0.

if you need more info, please ask.