Is copper EDTA safe for my tank

[gulfsurfer101]

Noticed this ingredient in Kent marine essential element supplementation and wasn't too shure what to make it. I haven't been able to pull up too much info on this stuff, at least nothing that will help me out so maybe somebody here knows what the long term effects of using this element are.

[supernip]

Im not sure what the biological function of it would be but I looked it up and here is the structure of it. Carbon and Hydrogen aren't represented.

 

 

Red is oxygen and blue is Nitrogen. It's got 1 valence electron so it's going to bind pretty tightly to oxygen's donors. A quick google search says the copper-EDTA complex is highly stable so my guess is it won't mess with the chemistry in your tank. My guess is that it's there as a counter ion

 

also intrawebs tells me its used in a lot of shampoos

[gulfsurfer101]

I read something that had to due with a binding agent as well I just didn't know what to make of it. I've been dosing it in every four days at 5ml in my 30g tank with no ill effects till I noticed a chalice of mine melting away from one side which led me to inspect things a little further. I belive the trace element had no part in it though and may have just been overlighting since the half that melted was in direct light and the other half that did not was beneath and shadowed by the top half of the coral.

[supernip]

it would retard the reactivity of the metal by trapping it

[lakshwadeep]

EDTA is the binding agent (chelant), and it's used with more than just copper in that kent product:

 

"Calcium Chloride, Cobalt Chloride, Iron EDTA, Lithium Chloride, Magnesium Chloride, Manganese EDTA, Nickel Chloride, Potassium Chloride, Potassium Iodide, Sodium Molybdate, Strontium Chloride, Zinc EDTA, Copper EDTA, and Potassium Bromide."

 

It's likely the metals are chelated with EDTA to avoid them precipitating out (forming an insoluble solid) inside the bottle with some of the dissolved anions (basically the second element/compound in each of the above chemical names). For example, copper(I) chloride is insoluble.

 

That said, in actual saltwater with many organisms, it could be that the EDTA degrades or is removed. Otherwise, there won't be any benefit to adding metals that are permanently bound and not available to be used.

 

The main reason you should avoid using essential elements is that you have to add all these chemicals in certain proportions, which could lead to excesses (including toxicity) or deficits due to them being used (or not used) at different rates.

 

It's a good idea to read this article on supplementation. The section on trace elements is useful since it singles out kent essential elements as an example of dangerous supplementation.

http://reefkeeping.com/issues/2007-04/rhf/index.php

[wombat]

EDTA is the binding agent (chelant), and it's used with more than just copper in that kent product:

 

"Calcium Chloride, Cobalt Chloride, Iron EDTA, Lithium Chloride, Magnesium Chloride, Manganese EDTA, Nickel Chloride, Potassium Chloride, Potassium Iodide, Sodium Molybdate, Strontium Chloride, Zinc EDTA, Copper EDTA, and Potassium Bromide."

 

It's likely the metals are chelated with EDTA to avoid them precipitating out (forming an insoluble solid) inside the bottle with some of the dissolved anions (basically the second element/compound in each of the above chemical names). For example, copper(I) chloride is insoluble.

 

That said, in actual saltwater with many organisms, it could be that the EDTA degrades or is removed. Otherwise, there won't be any benefit to adding metals that are permanently bound and not available to be used.

 

The main reason you should avoid using essential elements is that you have to add all these chemicals in certain proportions, which could lead to excesses (including toxicity) or deficits due to them being used (or not used) at different rates.

 

It's a good idea to read this article on supplementation. The section on trace elements is useful since it singles out kent essential elements as an example of dangerous supplementation.

http://reefkeeping.com/issues/2007-04/rhf/index.php

 

Wouldn't one just use copper (II) chloride?

 

I like this quote from that article:

 

If you believe that you need (or want to experiment with) trace elements (such as iron or manganese), my suggestion is to use single additives of known concentrations.

 

I've noticed positive results from Fe/Mn/KI dosing. There may be other more obscure trace elements that become limiting for SPS growth/coloration according to some folks...

[supernip]

iono I still think chelating agents reduce reactivity/de-activate metal ions

[wombat]

iono I still think chelating agents reduce reactivity/de-activate metal ions

 

From RHF:

It is a chelating agent with copper already attached, so it delivers copper when the chelate breaks down, which they are known to do in seawater exposed to air and light.

 

AFAIU the idea is similar to using an organic counter ion (like iron citrate, rather than iron sulfate) in that it will slowly introduce the ion of interest to the aquarium.

[supernip]

oh so it allows for a higher concentration/ distribution of the ion in the product without overt fear of overdosing?

[wombat]

oh so it allows for a higher concentration/ distribution of the ion in the product without overt fear of overdosing?

 

No, not at all. The total concentration is the same, but the amount that is available for corals to use is added slowly. If you added it with a freely disassociating counter ion (say chloride instead of EDTA) you get the full whack all at once. You can think of it like feeding your fish several small amounts rather than a big meal once.

 

Either way I have no idea whether adding copper is necessary for a reef tank. It could theoretically be too low (copper is necessary for life) in your aquarium but whether that's the case or not would need to be determined by testing. When it has been tested in reef tanks in past studies it's been higher than surface NSW.

[supernip]

thats what i meant

[wombat]

You can definitely still overdose it.

[supernip]

I was wrong then. Please post pictures of the frondosa-eschmeyeri babies

[wombat]

:lol: :lol:

 

[supernip]

in fact, can I has a pair? Im from san jose!

[skimlessinseattle]

Crap. Seems like I missed all the fun. EDTA is a ligand that will complex copper ions, rendering them quite less reactive to their surrounding environment. EDTA is very useful for heavy metal poisonings caused by lead, cadmium, and other nasty ions people have had the luck to ingest. The great thing about the EDTA molecule is that it loves to accept proton donors, and hates giving them up, so it's a fantastic method of removing harmful chemicals from a given system.

 

You swallow lead...oh no's...you swallow EDTA...yay! You make pee, and now you are all better. Your aquarium does the same.

[lakshwadeep]

Wouldn't one just use copper (II) chloride?

 

It depends on what they're being used for, and I don't know which oxidation state is actually used. AFAIK, the most RHF has written about copper was a tap water article that did not mention the specific oxidation states of dissolved copper. Cu²⁺, the more common oxidation state, may undergo different reactions than Cu¹⁺. Also, Cu²⁺ forms insoluble precipitates with carbonate and hydroxide, which makes adding it to saltwater a problem.

 

Also, higher oxidation states for metals leads to a greater likelihood of hydrolysis with water (and thus breaking up the metal-EDTA complex), but that may not be a significant factor.

 

Supernip: You're correct that chelation can be considered as "deactivating" the copper ion, which is why I suggested chelating copper would help avoid precipitation inside the bottle and why only some metals are chelated and others are in solution. Wombat's suggestion that chelation is for a slow release of the copper would depend on the rate of EDTA degradation in saltwater.

[Deleted User 6]

lak, you're probably the smartest person on this site. srs.

[lakshwadeep]

No, in this topic's case, my chemistry classes give me good background information on metals, EDTA, and chelation. Most of my info came directly from my quantitative analysis lecture slides since one of the experiments was to measure the calcium concentration in water using EDTA.

[Deleted User 6]

lak, you're probably the smartest person on this site. srs.

[wombat]

Also, Cu²⁺ forms insoluble precipitates with carbonate and hydroxide, which makes adding it to saltwater a problem.

 

When people add copper to seawater to treat parasites, they use copper (II) sulfate...

[supernip]

so where those rhinos at?

[wombat]

so where those rhinos at?

 

Sorry, but the babies were basically unrearable. I wish I had some photos of a hundred tiny juveniles but they only got to 11 days or so.

 

http://stickycricket.com/gallery2/main.php?g2_itemId=214

[lakshwadeep]

When people add copper to seawater to treat parasites, they use copper (II) sulfate...

 

And that's because copper(II) sulfate is soluble in water. After the addition, it's difficult to tell what/when reactions may occur or how much copper will remain dissolved. It would be useful as an experiment to measure the copper ion concentration in saltwater over time after adding a specific amount of copper sulfate.

http://www.massmind.org/techref/other/pond...ppersulfate.htm

 

Here's a good overview of solubility:

1. All sodium, potassium, and ammonium salts are soluble.

2. All nitrates, acetates and perchlorates are soluble.

3. All silver, lead and mercury(I) salts are insoluble.

4. All chlorides, bromides and iodides are soluble.

5. All carbonates, sulfides, oxides and hydroxides are insoluble.

6. All sulfates are soluble except strontium sulfate and barium sulfate.

http://www.csudh.edu/oliver/chemdata/data-ksp.htm

[wombat]

And that's because copper(II) sulfate is soluble in water.

 

But so is copper (II) chloride, right?

 

After the addition, it's difficult to tell what/when reactions may occur or how much copper will remain dissolved. It would be useful as an experiment to measure the copper ion concentration in saltwater over time after adding a specific amount of copper sulfate.

http://www.massmind.org/techref/other/pond...ppersulfate.htm

 

We've done that in the past to keep it between 0.17-0.22 ppm. This is the "safe" range for fish but will stop the life cycle of Cryptocaryon. If there's any calcium carbonate in the tank it will take a ton of copper just to get it above zero, but once you do the additions are fairly straightforward.

 

 

 

5. All carbonates, sulfides, oxides and hydroxides are insoluble.

 

Dunno what to make of that list, lithium hydroxide and sodium hydroxide are plenty soluble. And calcium hydroxide is of course soluble enough to make kalkwasser...