How to clean stubborn glass?

[Rocketcaver]

My brother gave me his large aquarium (18" H X 36" W X 12" D) and I hope to turn it into a terrarium. The problem is that the glass is stained inside and I can't seem to clean it.
It was covered in that crust you get when you leave an aquarium un-tended and just let all the water evaporate out (don't ask me how I know about that). Lots of elbow grease and baking soda has removed the crust, but there is still some kind of stain making a ring all the way around about half way up (inside). I even tried Lime Away, and so far that hasn't helped.
I know that glass can oxidize and that there is little hope of fixing that, but I really don't think that's what I have here. Or at least I hope not.
Any suggestions would be appreciated.
Sorry if this has been covered, I did a quick search and didn't find.

 

[Tony Paroubek]

razor blade.. if you cant remove it with a single edge blade on flat glass... it's in the glass

 

[31drew31]

Lemon juice and a razor blade has worked well for me

 

[RL7836]

razor blade.. if you cant remove it with a single edge blade on flat glass... it's in the glass

I have some pieces of glass that I use to cover terrariums & aquariums. Many of these develop a 'stain' that resists all conventional cleaning approaches. They seems to be etched in the glass. Since this 'etching' is not deep and it's in non-stressed glass, it would seem that it could be buffed out with some fine/ultra-fine grit. Has anyone done this before? If so, is it remotely cost-effective (after the learning curve has flattened out)? While glass is not all that expensive - purchasing, cutting-to-size & rounding 8 sides per piece of glass also requires a not-insubstantial chunk of time...

 

[Av8tor1]

I have used Dupont #7 automotive polishing compound

Apply, let dry and hand buff off.... just like car wax, a little work but makes glass look amazing
(the glass also stayed clean a lot longer, guess it removed some of the asperities)

I would think any automotive polishing/rubbing compound would give similar results

 

[Rocketcaver]

The razor blade didn't work. It looked good wet, but when it dried the stain was back.
I'll try the polish, thanks.

 

[dan d]

I have heard toothpaste works ? It's basically a polishing compound, but not to abrasive that it will scratch.

I have an old aquarium that is the same as you describe, when it's wet it looks great, when it's dry it has that haze to it. Thankfully I keep my terrium humidity up high enough it looks fine.

Dan

 

[boxofrain]

A wet scoth-brite pad may help, and will not scratch the glass.