Can I Use Galvanised Tanks for Grow beds ?

Galvanised tanks are coated with zinc. Over time the zinc coating oxadises and is leached into the water body, and zinc is well known to cause problems for fish.

The use of Galvanised tanks goes against common accepted knowledge and also a lot of research that can be easily accessed.
The way in which zinc affects fish is death by tissue hypoxia.
Below is some exerpts from a scientific jounal that should prove to be interesting on the subject.

Acute zinc toxicity to rainbow trout (Salmo gairdneri): confirmation of the hypothesis that death is related to tissue hypoxia Burton, DT | Jones, AH | Cairns, J
Journal of the Fisheries Research Board of Canada [J. Fish. Res. Bd. Can.]. Vol. 29, no. 10, pp. 1463-1466. 1972.

"Acute heavy metal toxicity to fish has been attributed to the coagulation or precipitation of mucus on the gills and/or to cytological damage to the gills. The physiological mechanism of death by either of the above causes is related to a breakdown in gas exchange at the gills. This study of acute zinc toxicity to rainbow trout (Salmo gairdneri) supports an earlier hypothesis that modification of the gas exchange process at the gills creates hypoxia at the tissue level. Tissue hypoxia appears to be a major physiological change preceding death once the gas exchange process at the gills is no longer sufficient to supply the oxygen requirements of the fish."

Hypoxia is a condition of oxygen reduction in humans and animals. As an example, mountain climbers can suffer hypoxia when climbing at altitude, which causes initially disorientation followed by nausea then ultimately death.

Research shows that as little as 35 thousandths of a thousandth part can be detrimental to fish.
So the fish will die exhibiting the same symptoms as if there is lack of dissolved oxygen in the water.
I would suggest that some folk have gotten away with using old galvanised tanks to date, because they have been raising Tilapia which are well known to be able to tolerate poor water quality and low DO levels.

Trout or Barramundi are at the other end of water quality needs and would quickly succumb to zinc poisoning if placed in a system that had galvanised tanks or grow beds..

Posted By Murray Hallam on 12th December 2011

Updated : 4th October 2013 | Words : 376 | Views : 2531

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