Rusty appearance to water

[Blueangel4730]

I have redone my 10g and have put slate in. I have noticed some rust color. My ammo is 0 and my ph is 6.0 please assist

 

[Zagz]

What are your other parameters (nitrate and nitrite)? How long was the tank set up? Usually a brownish appearance or rusty looking color is part of the process of setting up a new tank. It should go away on it's own. However if the tank was set up a while it might be something else.