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Leaking Stainless Fish Tanks

I work for a park that has two very large aquariums. The tanks were constructed in the early 1980's and their bottoms are composed of thin stainless steel. For many years, rocks sat directly on the metal and the result was electrolysis and pinholes.
A few years ago, other staff members covered the bottom with silicone and the rocks no longer touch the metal bottom. It seems to have worked, however, I wonder is there a better sealing product available? Due to cost, welding or replacement do not seem likely. Any suggestions, especially ones that will not kill the fish?

Kenneth A. Bausch
Army Corps of Engineers - Geyserville, California
2006

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2006

If the silicone is doing the job required, how could anything else be "better"?

What other characteristics do you want other than the tank bottom being sealed?

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.

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If the silicone sealant solves the problem, keep it. However, I am at a loss to understand how rocks can cause electrolytic corrosion, unless they contain a free metal or an anion that promotes corrosion of stainless steel. Nevertheless, if that is the case, so be it. You could put a good layer of gravel or sand over the siliconed base and this will stop the rocks from touching the steel base as well as make the base look more attractive and hence there will be no corrosion. If your rocks cause corrosion, I would throw them out and change them for ones that don't rot steel!

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2006