Advice on removing unknown substance from glass

[krishj39]

I just set up my 90 gallon. I used 50lbs argo sand, 50lbs silica (Quickcrete playsand), and 25 lbs CC. I started the tank on Sunday, and all Thursday I have had something precipitating on the glass. It is white, but I can still see through it. It looks like the tank got super scratched. Feels kinda that way too, actually. It just keeps growing. My theory is that something in my sand is reacting with my glass because it is only happening right above where the sand is. It feels as though it has actually bonded to the glass. It is definitely not organic. I have tried scrubbing it off, and it doesn't do any good. If you have ever felt what dried superglue feels like on a smooth surface, that is what it feels like. Anyway, I can't get rid of it by scrubbing. All I know to do is pray it doesn't keep growing and hope that eventually it goes away on it's own. Anyone have any idea what it might be and how to take care of it? I've never seen anything like it.
Kris
Unless someone can convince me otherwise, I have to believe it is from the Quickcrete Playsand.

 

[mr . salty]

If the tank is glass,you can use a razor blade to scrape it off..If it's acrylic,you should use a credit card(razor will scratch acrylic)

 

[krishj39]

Thanks salty, I completely forgot about razorblades, I guess that's what happens when I write posts too late at night.