Effects of metal in aquatic tank

[Mark]

Here's a question for all you chemistry boffins. I want to incorporate a structure into an aquatic tank which is held together using zinc coated steel rods. I assume the zinc coating will have a limited life and eventually the steel rods will rust once the coating has gone. What implications would the coating and rust have on water chemistry and health of inhabitants?

Thanks.

 

[eljorgo]

Hey Mark.
I really don´t think that the zinc coat will get destroyed just by contacting the water. In case of destruction of that layer the steel will be much more vulnerable and some part will start to seem rust. In that case some material will start to deposit in the bottom like Zn2O FeCO3 and Fe2O3 This last can be accepted by human beings up to 15mg/L. So Maybe not much impact in newts but if they take water to their lungs then I don't know.. The other two compounds may be lethal at lest the FeCO3 may cause a drop in p[H].
Also the H2O giving to the metals the O atoms will let some 2H+ in water witch is going to give a serious drop in p[H].
Hope I´ve gave you a hand
Chip.

 

[dipsydoodle]

I don't know what impact it would have on the health of the newts or any animal for that fact; I was told that newts were particularly susceptible to metals in the water and to be careful.

The zinc coating would breakdown on contact with the water; especially the bit that is on the water surface; the only metal that "shouldn't" rust in water is stainless steel - however at work we have a stainless steel letter box and it has rusted - I think technically it would still rust but it wouldn't rust as quickly. = I work for a company that specialise in corrosion and rust for the offshore industry :rofl:.

 

[Jennewt]

I have no relevant experience personally, but the Wright&Whitaker book declares that all metals are a no-no for amphibian tanks. They even say not to use metal screen lids.

"Plumbing fixtures composed of copper or zinc may leach enough metal into the water, particularly in recirculating systems, to cause toxicoses in fish (Klonz, 1993). Activated carbon is not a reliable adsorbent to remove all metal ions from water."

However, they also acknowledge that there haven't been any studies done in amphibians, except at very high metal concentrations, which are not generally relevant to husbandry.

 

[Mark]

Thanks folks, glad I asked! Perhaps it's safest to avoid metal rods entirely. The same rods are available in plastic so it's not entirely back to the drawing board.

 

[Decount062]

Normally ions are exchanged when metals are introduced into water,when there are pumps and other electronic devices in the tank these devices radiate small currents that increase this exchange of ions,this is known as galvanic corrosion.We then have to consider the chemical activity of these elements,basically a scale to judge how metals are affected by acids/bases/oxidation.Zinc is an especially poor choice(very active chemically) and rods of zinc are actually used to keep metal pump parts from corroding.Anything that can organically degrade will wind up in your water eventually,either dissolved,compounded or suspended.Don't forget, we try to mimic nature,would these conditions be considered natural?.Prevention is a lot easier than trying to figure what went wrong.

 

[dipsydoodle]

I'd definately go for the plastic rods; at the end of the day they will last longer; and they will be safer

 

[SludgeMunkey]

I would avoid metals too. Copper, lead, cobalt, nickel are prevalent in many modern alloys (not that this means anything, but When in doubt, leave it out.) Rust from iron breaking down will wreak havoc on your pump impellers in the long term.

 

[Lagid]

Hi,

I'm planning to build a big aquarium, using an aluminium frame in the front side. Do you know something about the aluminium toxicity?

Thank you.

PD: sorry for my poor english!!