Calcium on aquarium

[Jamelle14]

I recently bought a used tank, and it has calcium on the glass. I've tried vinger it didn't work, I've also tried lemon juice and baking soda and it still did not remove it. When I scraped with razor blade still did not work.
Any suggestions what I can do to remove it?

 

[Aiken Drum]

We had this thread recently has contains a couple of commercial products you havent tried.

Newbie - Hazed appearance to used aquarium

Hello.....I am a new member, thank you for adding me. I have just purchased a used aquarium at a garage sale. It appears to be in good shape and I filled it with water as soon as I got it home to verify it doesn't leak. However, the inside glass is very hazy near bottom. The hazy section is...

www.aquariumadvice.com

 

[Andy Sager]

You need to let these products sit on the glass for some time( 20-30 minutes minimum) before wiping or washing off before you conclude they don't work. That said, if the calcium has been there for a long time, it can etch into the glass and it will never get clear. I have some tanks like that. I just make the hazy side the back of the tank.