Black sand

[40galreef]

I am redoing a 40 gallon planted tank. It has had a lot of trouble with cloudy water. As I was taking it apart I found a lot of dark sand! What is this, and how can I be sure it doesn't happen again?

 

[GNarnian]

What was the substrate to begin with? Was it rock or sand? did you have anything in there that might have been ground down into grains like that?

 

[40galreef]

What was the substrate to begin with? Was it rock or sand? did you have anything in there that might have been ground down into grains like that?

It was sand to begin. I has nothing that could have ground down.

 

[bigbanker]

That looks like mulm. Is it gritty at all?

 

[40galreef]

That looks like mulm. Is it gritty at all?

Yes, it was very gritty

 

[librarygirl]

Did you use any root tabs for plants? That can cause the discoloration. If not, sometimes gas pockets can form in the sand when it isn't stirred up occasionally. Does it smell like rotten eggs? There's some debate on how deadly these pockets can be for fish. In the future just disturb the sand once in a while, run your finger or a plastic fork through it so it doesn't settle and build up gasses.