New Filter Socks

[Scubajoe1]

OK. I'm really not sure what is the issue with my tank. Analytical chemist here so I am nuts when it comes to testing my water quality and everything seems to be honed in great. My tank is about 10.5 months old and the parameters are rock solid with the following

Nitrate 1ppm (red sea pro kit)
Alk- 9.4 (hanna)
pH 8.2-8.4 (Apex controller)
Ca- 440 (Hanna)
Phosphate 0.02 ppm (Hanna ULR phosphorus)
Mg 1350 ppm
Salinity 1.026

I am dosing and parameters are pretty solid.

So I cannot explain why I have a very dark color on certain areas of my substrate. It does not look like diatoms and my sand bed is about 1-1.5". I have lots of critters crawling around at night but cannot explain this dark matter.

Secondly I just lost a torch coral recently and other things are not looking great. I spoke to folks at vivid aquariums and they asked if I used new filter socks lately and did not wash them first. Actually I did just get new ones (like 8) about 2 months ago. I put the new filter sock in without washing it. I did not think there would be chemicals on it but I guess it is possible and that may be nuking some corals.

Does anyone know if this could be the case?

Secondly here are some pics of the black stuff on my substrate. Does not look like algae or diatoms. Anyone know what this could be?

Thanks

Joe

 

[seamonster124]

that's not just coraline on the crushed coral?

 

[Scubajoe1]

no it's like a black color. Looks a little purple because of the lighting.