Question: Black particles and murky water

Hey all

I keep finding small black bits of something all over my sand. It looks similar to the sand, but is lighter, so sits on top and is easily disturbed and floats around the water.
If left, it makes my water get quite murky, in a black sort of colour, unlike the usual green of a dirty tank.
If I leave the filter off, sometimes simply for the duration of the night, I wake and the water is incredibly black and murky.
It has happened twice. The first time, I sucked out as much as I could, but it seems to keep coming. I then siphoned out all my sand and water, rinsed the sand a lot, and put it all back in with fresh water.
I noticed it again recently, only about three months later, and have been doing larger water changes. I decided on a 3/4 water change, to get my tank clean, and it blossomed in a week and went very murky.
I've since decided to remove all the sand permanently, wiped down my tank and filled it back up.

I'm just wondering if anyone knows what this is? It doesn't wriggle around, but it starts to coat things. I washed all my ornaments and the week later, they had it all over them again. Is it some kind of algae?

I'm worried because I'm out of the country for four months and my less experienced partner is looking after my lotls. I don't want the black stuff to respawn and him have to deal with it

Hey there,

I must admit I get the odd few flecks of black that settle on the sand in my tank but it's always looked like a little broken down debris to me.

I havn't had any problems with algae personally but you could always cut down the natural lighting and see if there is any improvement? Or ask your partner to if you are away, as you said. I don't suppose you took a picture by any chance?

The room is pretty dark already, so I don't know if that would be the cause. I didn't unfortunately, but I probably should have!

How deep is your sand?

You shouldn't turn your filter off. Turning it off can kill your beneficial bacteria (which need fresh water for food and oxygen), and when you turn it back on, you blow all that dead bacteria and their waste products back into your tank.

The sand wasn't more than 3cms deep. It would pile up in the center but I always moved it back to the sides and raked through it.