water stains

I currently have a 55 gallon up and running. I’ve been wanting to buy a new tank that’s drilled and go bigger. I just bought a 90 gallon tank off Craigslist. It has hard water stainson it.. at least that’s what I think it is. And I can’t get it to come off to save my life... I’ve heard vinager...

I currently have a 55 gallon up and running. I’ve been wanting to buy a new tank that’s drilled and go bigger. I just bought a 90 gallon tank off Craigslist. It has hard water stains on it.. at least that’s what I think it is. And I can’t get it to come off to save my life... I’ve heard vinager...