So I've had my new Eclipse 5 gallon corner tank set up and going through a fishless cycle for about 40 days now - I did a large water change today and when the water was stirred up, there were black particles floating all around in the water! They range from very small (think large bits of dust) to a bit bigger, and there are so many of them! I gravel vacuumed a bunch of them out during my water change, but many more were stirred up in adding the new water! And I can see that the edge of the filter itself nearest the input from the tank is black tinged, making me think it's been filtering these black bits out already. But it's far from getting all of them!
Does anyone know what this could be?? I have no decor in the tank that could have fragments falling off of it, and this is not gravel dust (my gravel is purple, not black and was rinsed ridiculously before I put it in, and the black bits float a bit more lightly than gravel particles, which I've seen in other thanks)
I'm hoping it's something harmless like carbon from the filter (at least, I assume that's harmless....). Any input is uber appreciated!