Article on EDTA

[Caliban07]

Has anyone seen this? Or even aware of the potential implications of consistent use of EDTA not just for aquarium water conditioners and micro Fertilisers but products in general.

EDTA: the chelating agent under environmental scrutiny

 

[flchamp89]

It hot topic in my world last 15 yrs. Its gotten better but us still pretty common. Years ago its was often believed to be (filler) or part of the other (inert) ingredients on some products

 

[Caliban07]

I'm concerned at how the ions interact when EDTA is used and the fact I'm pouring it down my drain every water change.

 

[Delapool]

It seems pretty wide-spread in use?


http://scifun.chem.wisc.edu/CHEMWEEK/Chelates/Chelates.html

 

[Caliban07]

It is. It's in many things. Detergents, cosmetics etc and it doesn't get removed at the water treatment facility. Highest is in UK surface waters.

Be interesting to see if there was any in my tap water.

My main concern (environment aside) is what the EDTA is doing to mobile elements within my tank. It has very low biodegradability and so it may be hanging round. How do this interact with soil cations. Does it move them from soil solution and bind the tightest binding elements leaving the weaker behind. Does it interfere with plant uptake or antagonise toxicity?

Really interesting. I have been very lazy with my water conditioner measurements. How much of that solution is a strong chelate? I'm sure prime uses EDTA?

When you look at the actual percentages of dry trace mixes they are very low. Probably amounting to as little as 10-15% (pure guess) of the powder. Guess what the rest is? [emoji15]

 

[flchamp89]

Very few know these answers. The ones that do arent going to let that info out

 

[Polycomb71]

EDTA chelates divalent cations, like Calcium and Magnesium. AFAIK, prime has bisulphite compounds in it. But yes, I have noticed EDTA in so many cosmetics related products.

 

[Delapool]

I think I saw somewhere that when bound to elements it is fairly harmless to plants. When a pure? product it can cause issues. Also that plants somehow have no trouble extracting elements out of synthetic chelating agents into organic chelating agents to move around (off top of my head from reading).

 

[Polycomb71]

I am a biologist by profession. In our kind of research, use of EDTA in many of the buffers is indispensable. But we use masks and protective eyewear when we weigh this thing out. Quite hard to dissolve in water, and solubility is rather poor below the pH of 8.

 

[Caliban07]

My understanding Is that EDTA has a higher affinity for other cations in an order such as

Iron (ferric)
Copper
Nickel
Cobalt
Iron (ferrous)
Zinc
Cadmium
Manganese
Magnesium
Calcium

Therefore because we have a lot more calcium and it is the least tightly bound there may be more in solution.

If EDTA isn't easy degradable does it just hang around sequestering any new nutrient additions and how does this effect cations bound to humic substances?

Once the chemical bond is broken and the element is used up what happens to the EDTA. Does it go again?

In soils humic substance bind metals according to the lyotropic series and can be broken by relevant microorganisms at the the plant roots which enables uptake (Walstad ecology of planted tank)

How does this effect soil cations and the uptake of plants? If EDTA is harmful or toxic to bacteria how is this effecting our ecosystem?

When I cation is broken from a soil colloid by biological means does any excess EDTA in the soil solution just say 'cheers I'll have that sorry plant?'

I know these answers will never materialise but you get my point. Why are we adding something to our tank we know so little about?

Would it be better to add small amounts of unchelated micro nutrients such as boric acid or copper and zinc sulphate?

 

[flchamp89]

http://edis.ifas.ufl.edu/m/#publication?id=HS1208

Try page 2....helps some

 

[Caliban07]

Cheers champ. No more EDTA for me.