Copper and fish

[M Cosmo]

I want to add a heater to my fish tank and it has a small temp sensor. Here is a pic.

It is about 4 inches long. Will this small amount of copper poison my fish. I have about 600 gallons or more of water in the system.

Ron is using the same heater and he encapsulated his in a bottle and sealed it.

I was thinking of just painting mine with some clear since it won't be hotter than 80 in the tank.

[TCLynx]

Remember that it is not just the danger directly to your fish but also the corrosion of the metals causing the equipment to fail that can be a problem too.

What are the other metals there? Stainless steel is the only one that I would trust. The heating element is what?
The metal that it is all attached to is what?

[Chi Ma]

You would have to paint the capillary tube also. Remember the sheet metal is galvanized which has zinc in it.


A little blurb from here: http://www.lenntech.com/periodic/elements/zn.htm


Effects of zinc on the Environment

The world's zinc production is still rising. This basically means that more and more zinc ends up in the environment.

Water is polluted with zinc, due to the presence of large quantities of zinc in the wastewater of industrial plants. This wastewater is not purified satisfactory. One of the consequences is that rivers are depositing zinc-polluted sludge on their banks. Zinc may also increase the acidity of waters.

Some fish can accumulate zinc in their bodies, when they live in zinc-contaminated waterways. When zinc enters the bodies of these fish it is able to bio magnify up the food chain.

Large quantities of zinc can be found in soils. When the soils of farmland are polluted with zinc, animals will absorb concentrations that are damaging to their health. Water-soluble zinc that is located in soils can contaminate groundwater.

Zinc cannot only be a threat to cattle, but also to plant species. Plants often have a zinc uptake that their systems cannot handle, due to the accumulation of zinc in soils.

On zinc-rich soils only a limited number of plants has a chance of survival. That is why there is not much plant diversity near zinc-disposing factories. Due to the effects upon plants zinc is a serious threat to the productions of farmlands. Despite of this zinc-containing manures are still applied.

Finally, zinc can interrupt the activity in soils, as it negatively influences the activity of microrganisms and earthworms. The breakdown of organic matter may seriously slow down because of this.



Read more: http://www.lenntech.com/periodic/elements/zn.htm#ixzz16zkY0NNW

[David Hart]

Hi Michael, How about dipping it into a can of 'liquid rubber'...they sell it to dip the handels of your tools. I also used it on the wirring conectors of my boat trailer.
It wouldn't be 'as sensitive' with it's tempt readings....the rubber would insulate it some. Might hold up better then the clear paint (?)

[RupertofOZ]

Copper is a soft metal, and ionises into soluble form readily in acidic conditions... like we tend to have in aquaponic systems.

Copper is extremely toxic to crustecea... and will kill them in a blink of an eye... and isn't much more tolerable for freshwater fish... especially those intended for human consumption...

Yes, copper sulphate was once used to treat aquaculture ponds... but is now banned...

And yes, it is still used to treat ornamental fish... as are a lot of other lethal carceoginic treatments... all of which have been banned for use with fish destined for human consumption...

Copper Sulphate was the principal ingredient is marine anti-fouling paints... and again, has now been banned... as it resulted in the complete destruction of marine life in marinas....

In general... don't use any aquaria based products in AP.... and in particular... don't use copper or zinc...

Kobus Jooste said:

If I may be the voice of ignorance in this thread. Zinc and Copper become toxic if present in large amounts, but are also trace elements needed by living organisms. In fresh water aquariums we used copper-based medication straight into the water to deal with a great many illnesses related to parasite infections. Invertebrates does not like copper in high volumes and your worms may be the first to be affected by it. Looking at the size of the copper element and the volume of the fish tank, I'm nit sure how much will have to leak though. Same philosophy on the zinc. I'll do a search on zinc and copper toxicity if I have a gap today as it may be a recurring question. People get very sterile when they do AP, but if you look at nature - rock and soil, you will find these elements. It all boils down to the amount that is going to escape into your set-up.

[RupertofOZ]

If you "google" ... "copper toxicity to fish".... you'll get squillions of hits... of peer reviewed papers dating back 50 years... showing copper is toxic to most fish at very low levels... and crustacea at miniscule levels...

[RupertofOZ]

Kobus Jooste said:

Freaking out if your house is like mine and water is delivered through..........you guessed it: Copper pipe. Is my rain water safe if it was captured on a zinc-plated roof?

Yep, you should be freaking out... all copper piping is now banned in OZ... now replaced with high pressure PVC tubing... and galvanised zinc roofs are a known problem...

[RupertofOZ]

As an aside... it has been shown in many studies that Calcium hardness significantly affects survival of juvenile
fish exposed to a toxic concentration of copper sulfate in low alkalinity water.

But, magnesium hardness provided no protection from copper toxicity.

Note... the studies refer to low alkalinity water... low pH...

Calcium Hardness is a measure of carbonate buffering in the system....

Magnesium hardness is a measure of the mineral content of the water, usually Calcium * Magnesium... and known as general hardness, often referred to as "hard water"

Sorry Kobus... but I'm going to have to agree to disagree.... the studies relating to copper toxicity... are long and varied... and consistant...

Bare in mind that AP systems are recirculating by nature.... and almost all metals are cumulative in fish protein...

Put copper & zinc in your systems if you want... I wont!!!

[RupertofOZ]

Every single person I know that's exposed their AP system to copper, or zinc... has ended up with dead fish... and usually within a month, or two at best...

[Harold Sukhbir]

There are already high levels of PCB's and mercury in farmed fish according to aquaculture studies, where system water is exchanged and changed on a regular basis!.Of course, the major source coming from commercial fish food pellet. Farmed fish have even higher levels than wild fish which store in their fat. I agree with Rupert especially when we consider AP being a true RAS environment. We already have major toxic inputs inherent in our AP systems, wisdom demands we limit the introduction of anything additional, don't you think? The present safety recommendation allows for consumption of one farmed salmon per person per month.

Bare in mind that AP systems are recirculating by nature.... and almost all metals are cumulative in fish protein...

RupertofOZ said:

As an aside... it has been shown in many studies that Calcium hardness significantly affects survival of juvenile
fish exposed to a toxic concentration of copper sulfate in low alkalinity water.

But, magnesium hardness provided no protection from copper toxicity.

Note... the studies refer to low alkalinity water... low pH...

Calcium Hardness is a measure of carbonate buffering in the system....

Magnesium hardness is a measure of the mineral content of the water, usually Calcium * Magnesium... and known as general hardness, often referred to as "hard water"

Sorry Kobus... but I'm going to have to agree to disagree.... the studies relating to copper toxicity... are long and varied... and consistant...

Bare in mind that AP systems are recirculating by nature.... and almost all metals are cumulative in fish protein...

Put copper & zinc in your systems if you want... I wont!!!

[Ron Thompson]

I first tried just wrapping the copper thermostat in a strip of duck tape - but it would not turn on. After looking at the directions for the unit it says the lead must be in water to work; it will turn off in air as a safety feature. So I concluded that there is some type of electrical switch that must be shorted by the water to work. Therefore I put the lead in a glass bottle, filled with water, sealed the top and submerged it the tank. The water in the bottle is isolated, so no copper issue. It is also held at the same water temp as the tank by conduction.

Michael, I would be hesitant to seal the lead with any coating due to the apparent short switch on it.

I also removed the galvanized shield as it is strictly a safety feature to keep livestock from burning their noses. The fish have not had a any issues with the bare heating element (which is stainless steel).

[M Cosmo]

Ok that sounds good. I think I will set it up tonight.

[Harold Sukhbir]

One of the immediate issues concerned with is the effect of leaching and it being taken up in plant and fish.When we look at concentrations building over time in a Recirculating system the picture changes. I think in Ap we aren't allowed the luxury afforded to the other types of agriculture.What goes into our systems not only stays there but ever so slowly builds into toxicity.

Kobus Jooste said:

Let me re-focus my replies in this debate. I know the studies concerned with copper and zinc paint a bleak picture of the two elements. Also that they are most dangerous in acidic, unbuffered environments. That said, many parts of the world, including my house, have copper pipes and galvinized iron roof sheets. I am willing to have tissue samples of any dead fish sent of for analysis, as it is of interest to me too - Just none of them had died yet. For me, at my setting, these two elements are difficult to avoid. Animals and plants require copper and zinc to grow. Below is an abstract of a paper on copper requirements of plants:

Abstract
The copper (Cu) requirement of four crop species was measured in a glasshouse experiment using yield of dried shoots and Cu content (Cu concentration multiplied by yield of dried shoots) of 62 day old plants grown in two different alkaline soils. The species compared were faba bean (Vicia faba L. cv. Fiord), chickpea (Cicer arietinum L. cv. Tyson), lentil (Lens culinaris Medik cv. Digger), and spring wheat (Triticum aestivum L. cv. Stretton). The comparative Cu requirement of the species was determined from yields of dried shoots when no Cu fertilizer was applied, the amount of applied Cu required to produce the same percentage of the maximum (relative) yield of dried shoots, and the Cu content of dried shoots. The concentration of Cu in youngest tissue and in dried shoots was used to determine critical concentrations of Cu in tissue associated with 90% of the maximum yield. Faba bean used indigenous soil Cu more effectively than wheat, followed by chickpea and then lentil. As measured using both shoot yield and Cu content in shoots, the Cu requirement was lowest for faba bean, and increased in the order faba bean < wheat < chickpea < lentil. Copper concentration in dried youngest tissue and in dried shoots increased with an increase in the amount of added Cu. The critical Cu concentration in the youngest tissue was (mg Cu/kg): 4.6 for lentil, 2.6 for chickpea, 1.5 for wheat, and 2.8 for faba bean; corresponding values for dried shoots (mg Cu/kg) were 6.3 for lentil, 3.3 for chickpea, 2.8 for wheat, and 3.0 for faba bean.
Keywords: Copper requirement; Pulses; Spring wheat; Critical Cu concentration


I have also attached a short paper on zinc requirements of plants. What an interesting debate this can spark: Does the copper and zinc needs for a planted AP system exceed the levels that can leach from a house with a steel roof and copper pipes? I have not been able to get hold of exact data on fish, human zinc and copper needs, apart from picking up that these elements cannot be synthesized and therefore has to come out of our diet.

This is the basis for my lack of hysteria on the topic. Everything needs these elements in moderation. Let us establish what is moderation and what is risk, in stead of just going ballistic at the mentioning of their names.