Tough Hard water stains on aquarium?

Question

I recently was given a 6ft 125 gallon aquarium and can't get the glass to clear up. I work in a scientific setting and have access to strong acids and the protective equipment/training to use them and have tried the following.

*Using vinegar - gallons of it with the aquarium on its side.
*1 gal of 12 Molar hydrochloric acid mixed 1 with 1 gal of distilled water with the aquarium on its side,let is set for hours then up righted it and filled with water let it set for weekend.
*Used over the counter lime remover.
* razor blade/nylon sponge scraping.

All of these have done NOTHING
Don't know what else to try and I am starting to think the guy that gave it to me frosted the glass somehow. But the marks are very stratified and suggest typical stains left by evaporation.

I know it will take months of water changes/rinses/carbon to get this thing safe so don't give answers based on how dangerous this it to the fish. I'm willing to take the time to clean it back to "safe"

Answer 1

You may not have hard water stains. Do you know if the tank was ever used to house cichlids or saltwater fish? Both of these require a higher pH than other tropicals. As pH increases, silica (including aquarium glass) becomes more soluble and, in essence, etches the glass. If the person who owned it previously wasn't timely in keeping up with water evaporation in the tank, as the water level at the top changes, the etching would have a "layered" effect, at least near the top of the tank.

There's not really a lot you can do to get rid of these marks. I've heard flame-polishing the glass will work, but is not something that should be done other than by a professional. As long as the tank is filled with water, the marks are "somewhat" less noticeable, except where the "layering" occurs. It doesn't hurt the fish, just cuts down a bit on the visibility. I'd give it a few good rinses to make sure your previous cleaning attempts are all wahed out, fill it up with water, and use it.

Answer 2

I have kept fish for decades and have seen literally thousands of tanks in shops, homes (including my own), schools and wholesale environments with exactly the same problem. Best of luck finding a solution, I never have even in a lab environment. Once you find the answer, market that baby! lol

Perhaps a glass manufacturers R&D department could help?

Sorry I couldn't help

Answer 3

Vinegar and elbow grease will clean It up well