[ubstrong]

I know this is a thread that has been hashed and re-hashed. I can't find the answer tho, so here goes..
I was given some used tanks. They're in great shape except for "haze".. Mineral build up, i suppose. I've tried comet, phosphoric acid, vinegar, and elbow grease. now on to something stronger. If anyone has tried something that works, let me know

 

[gardennub]

Hey, this was in one of the sticky threads...
http://www.dendroboard.com/forum/parts-construction/12562-clean-glass-last.html

Essentially, lemon juice or vinegar and a razor blade are all you need.

 

[Pumilo]

If the lemon juice and razor blades won't do it, then it is probably etched into the glass and won't come out.

 

[Mr. elder]

10000 to 20000 grit sand paper. what we would use on acrylic tanks. than a fine buffing agent.don't know if it would work on glass. I'm sure it would be allot more work then acrylic. good luck

 

[Yobosayo]

Try a claybar