Hard to remove spots

[nick h]

I have these spots inside my empty tank that I can't seem to get ride of. I tried a razor blade and I read online to put vinager over them for a couple hours then wipe them off but that did no do the trick. They are all pencil earaser to quarter size, and there are about 100 of them total. Any ideas? Thanks

 

[ejaramillo01]

Some times these spots are not visible once the tank is full with water.

Try and see.

 

[Amicus]

Some of these may be calcium deposits. I have seen this in saltwater tanks before. Fill the tank and see if they are gone or magnified. If still there then a razor is your best bet, with a little elbow grease.