cleaning second hand tank

On Tue, 18 May 2004 20:19:11 +1000, "Desmond Wong"
bubbled forth the following:

Thanks for all the messages everyone.

I had tried vinegar to no luck with these stains... I have found out that
these marks have been there for about 2 years or so and never cleaned.

I have also used CLR with no luck, even UNDILUTED (I know, a bad thing to
do) and washed off excessively it still has left the marks on the tank, it
appears
to have made no difference to the appearance.

I will see how a very light coating of stove cleaner will go on it tomorrow,
obviously washed out very well afterward. I am preparing the tank for
probably about 2 months away, so plenty of time to do many rinses and washes
and testing before putting anything "live" in there...

Thanks again for all the responses.

It's sounding like the glass has actually been etched by the deposits,
especially if they were left on the glass for long periods of time. I
suspect polishing will be the only way to remove them, but maybe the
oven cleaner will work. Definitely let us all know if it does.

The following technical note from Pilkington describes several
processes that can stain glass. While intended for window glass, the
following paragraph from page 2 is applicable to aquariums:

"Even water alone can be damage the surface of glass. Certain types of hard water, for instance, may
leave harmful deposits if allowed to dry on glass surfaces. These deposits can be formed in washing or
rinsing the glass, or accidentally by the evaporation of water from such sources as lawn sprinklers. It is
difficult or impossible to remove such residue without excessive polishing."

The complete article is he

http://www.pilkington.com/resources/...ss20020306.pdf


Good luck!

Jerry