Opaque Buildup on glass

[rob safron]

So I have a glass aquarium and have been getting a semi-clear, semi-opaque buildup along the water line and just an inch or two below the surface. I have tried various scrapers, razor blades with no luck removing the build-up. Tried using vinegar on a sponge and scrub when doing a water change. I have dug and scraped a razor blade across it and can not get rid of this hard buildup. It has been growing down over time and hurting the view. Any idea's on how I can get rid of it??

 

[sbash]

Can you post a picture?

Also, describe your equipment in use? (skimmer, reactors, dosers, etc...)

 

[rob safron]

Really can't get a good pic. Parameters are Alk 7.5 CA 430 Mg 1400. I dose vinegar so phosphate and nitrate are near undetectable by tests. Feed very heavy as well as dose Aquaforest 3 part, reef energy and occasion reef chile. I guess it has to be some sort of calcium buildup but again somewhat opaque, not solid white. Very hard substance whatever it is. Not sure there is a reef safe solution. Tried wiping vinegar over and over then scraping with no result on last couple water changes.