White Matter

[wardcarrie5]

I have a white matter growing on my substrate. I try to vacuum it up but keeps coming back any idea as to what this is?  My tank is well established and no issue with ammonia/nitrite or nitrates. 

[Beau Burkhalter]

Looks like it’s just build up of gunk. Just keep gravel vacuuming

[wardcarrie5]

I’d normally agree but I’ve been vacuuming regular and it’s growing across substrate. I had even vacuumed up much of the gravel and replaced it and within a week it was all grey again. 

[gardenman]

It could be sloughing off the white rocks in the tank.

[Lifeisgood]

Can’t tell from the picture if it is exactly the same kind of thing I had going on in my tank or not.  But it turned out to be that I had a gypsum rock in my tank that was melting.  I thought it was some kind of fungus but it wasn’t.  Ended up vacuuming out the affected substrate and the remains of the gypsum rock.  
Does the water have a sulfur odor to it?

Are your white rocks soft enough to scratch into their surface with your fingernail?