EDDHA 6% chelated iron: dark red powder presented in a laboratory dish

EDDHA 6% chelated iron: dark red powder and its dissolution in water, producing a red-orange colour

Chelated iron (iron chelate) EDDHA 6%

$8.00

Weight	Price	Price per kg	vs 100 g
100 g	$8.00	$80.00	—
500 g	$20.00	$40.00	−50 %
1 kg	$31.00	$31.00	−61 %
2 kg	$57.00	$28.50	−64 %
5 Kg	$88.00	$17.60	−78 %

This EDDHA chelated iron at 6 % corrects iron deficiencies in plants, including in hard water, as it remains soluble up to pH 9. The powder dissolves in the system water or can be sprayed onto foliage, and the red tint it gives the water for a few days is harmless to fish.

Ref. FER-EDDHA-6-500·Chelated iron

Weight : 100 g

100 g

500 g

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The summary

What the sachet contains: 6% iron chelated by EDDHA, a powder that dissolves up to 120 g per litre of water.
EDDHA, DTPA or EDTA: EDDHA holds up to pH 9, DTPA up to 7.5, EDTA up to 6.5.
How to spot the deficiency: young yellow leaves and veins that stay green, generally below 1.5 mg of iron per litre.
How much to add: 33 g per 1,000 L roughly every 3 weeks, which adds 2 mg of iron per litre, or 20 g (1.2 mg) when the test still reads about 1 mg.
The water turns red, and the fish: a normal colouring that lasts a few days, and a working dose far below the toxicity threshold measured on trout.
Pack sizes: 100 g, 500 g, 1, 2 and 5 kg, shipped from France.

Iron chelate stable up to pH 9, for hard water and alkaline systems

EDDHA 6% chelated iron corrects iron deficiencies in soilless crops with alkaline water, because EDDHA stays soluble up to pH 9, compared with 7.5 for DTPA and 6.5 for EDTA. The reference dose is 33 g per 1,000 L about every 3 weeks, giving 2 mg of iron per litre, to be adjusted according to a measurement of dissolved iron.

EDDHA chelated iron is a mineral supplement for soilless crops whose water is too alkaline. In your system, the iron is often there but precipitated, in a form the roots can no longer absorb. The EDDHA chelating agent locks it inside a molecule that keeps it soluble and available to plants up to pH 9.

⚖️ EDDHA, DTPA or EDTA

All three supply iron, but the pH range in which they stay effective differs. EDTA loses its effectiveness above pH 6.5, DTPA holds up to about 7.5, and EDDHA remains effective up to 9. An aquaponic system most often sits between 6.4 and 7.5, and higher with hard mains water. If your pH falls outside this range, the article on pH regulation in aquaponics deals with the cause.

EDTA 13 %

EDTA has the highest iron content of the three, for soft water below pH 6.5.

DTPA 11 %

DTPA, the chelate of choice for managed systems, remains effective up to around pH 7.5 and leaves the water colourless.

EDDHA 6 %

Lower in iron per kilogram, EDDHA is the only one of the three that remains stable above pH 7.5. It turns the water red.

Test the iron level before each application

A colorimetric iron test gives you the dissolved iron level before dosing, then again 24 to 48 hours afterwards. Since 33 g of this chelate adds roughly 2 mg of iron per litre in 1,000 litres, and 20 g roughly 1.2 mg, this reading tells you whether you need a full dose or a reduced one. That way you avoid building up chelate in the water with no benefit to your plants.

🌿 Signs of a deficiency

The sign shows on the young leaves. The leaf blade yellows while the veins stay green and form a network: this is iron chlorosis. It appears below 1.5 milligrams of dissolved iron per litre, when the target range is 2 to 3. It affects the top of the plant first, because iron moves very little from older leaves to young shoots. A colorimetric iron test will confirm it.

The water takes on a red tint after each application

A few minutes after application, the water takes on a cherry-red to orange tint. This is the colour of the iron-EDDHA complex in solution, and it fades as the plants take up the iron. For an ornamental aquarium or a prominently displayed pond, DTPA 11 % delivers the same iron without any discolouration.

🐟 Iron in an aquaponic system

Fish feed provides little iron and your plants use it up with every growth cycle, so it needs topping up regularly. Allow 33 g per 1,000 litres roughly every 3 weeks, which adds 2 mg of iron per litre, and only 20 g when the test still reads about 1 mg per litre. Dissolve the powder in a little warm water, then pour it in with the pump running. The guide to iron deficiency in aquaponics will help you tell this symptom apart from a manganese or magnesium deficiency.

Technical specifications

The essentials

Iron content: 6% chelated FeThat is 60 g of iron per kilogram of product.
Chelating agent: EDDHAEthylenediamine-N,N'-bis(2-hydroxyphenylacetic acid), sodium salt. CAS 16455-61-1.
Stability pH: 4 to 9Above 7.5, it is the only one of the three chelates in the shop that still holds up.
Shape: Dark red microgranular powder
Water solubility: 120 g per litre at 20 °CWell above any realistic application rate: the powder dissolves completely.
Reference dose: 33 g per 1,000 LAdds 2 mg of iron per litre, about every 3 weeks. 20 g, or 1.2 mg per litre, is enough when the test still reads about 1 mg.

What it does in water

Target dissolved iron: 2 to 3 mg per litreHydroponic references recommend 1 to 3 mg per litre depending on the crop.
Threshold at which symptoms appear: Approximately 1.5 mg per litreBelow this level, chlorosis becomes visible on young leaves.
Water discolouration: Cherry red, a few daysThe natural colour of the iron-EDDHA complex, this is not precipitation.
Effect on pH: No noticeable effectThis product is not a pH corrector.
Root application: Dilution in the system waterPre-dissolve in a little warm water, then pour in with the pump running.
Foliar application: 1 to 2 g per litre of solutionSpray out of direct sunlight, wetting the undersides of the leaves as well.

Safety and storage

LC50 rainbow trout: Above 100 mg per litreMeasured at 96 hours. The reference dose of 33 g per 1,000 L corresponds to 33 mg per litre.
CE50 daphnia: Above 100 mg per litre48-hour measurement on Daphnia magna.
Classification: Not classified as hazardous
Handling precautions: Avoid dustWash your hands after use: the dye stains skin and clothing.
Storage: Dry, cool and ventilatedMoisture causes the powder to clump and makes dosing imprecise.
Yield from a 1 kg bag: Around 30 applicationsAt the reference dose of 33 g per 1,000 litres

To budget for separately

Kitchen scales: Weighed to the nearest gram
Iron test: Colorimetric iron test

12 further specifications are available in the detailed view.

In the box

1 resealable sachet of EDDHA chelated iron 6%, in the pack size of your choice

Iron content, form, solubility, ecotoxicity and storage conditions: safety data sheets from Fe-EDDHA 6% manufacturers. pH ranges recorded on 25/08/2026 from Van Iperen and Custom Hydro Nutrients.

EDDHA, DTPA or EDTA: which one for your water

All three supply iron. What sets them apart is the pH beyond which they can no longer hold it.

All three provide iron, across different pH ranges Beyond its limit, a chelate releases its iron, which precipitates and becomes unusable. Measure your pH before buying, as the choice of chelate depends on it.

	Upper pH limit	Still effective at pH 7	Iron content (%)	Leaves water colourless	Powder for 1,000 L at 2 mg of iron per litre (g)	Price	pH range where iron remains available
Recommended EDDHA 6 %Your choice	9	Yes	6 %	No	33 g	$31.00	4 to 9
Chelated iron (iron chelate) DTPA 11%Your choice	7,5	Yes	11 %	Yes	18 g	$38.00	4 to 7.5
Chelated Iron EDTA 13%Your choice	6,5	No	13 %	Yes	15 g	$27.00	4 to 6.5

EDDHA 6 %Recommended

pH stability

Upper pH limit9

Still effective at pH 7Yes

Concentration and quantity

Iron content (%)6 %

Leaves water colourlessNo

Powder for 1,000 L at 2 mg of iron per litre (g)33 g

Price

Activity range

pH range where iron remains available4 to 9

Chelated iron (iron chelate) DTPA 11%

pH stability

Upper pH limit7,5

Still effective at pH 7Yes

Concentration and quantity

Iron content (%)11 %

Leaves water colourlessYes

Powder for 1,000 L at 2 mg of iron per litre (g)18 g

Price

Activity range

pH range where iron remains available4 to 7.5

Chelated Iron EDTA 13%

pH stability

Upper pH limit6,5

Still effective at pH 7No

Concentration and quantity

Iron content (%)13 %

Leaves water colourlessYes

Powder for 1,000 L at 2 mg of iron per litre (g)15 g

Price

Activity range

pH range where iron remains available4 to 6.5

pH limits recorded on 25/08/2026 from Van Iperen and Custom Hydro Nutrients. Quantities for 1,000 L calculated on the iron content of each product.

Estimate your
delivery time

EDDHA iron chelate is a powder not classified as dangerous for transport and is shipped as a standard parcel from France. The stated timeframe covers order preparation, not transit, which depends on the carrier selected at checkout. Exact rates are displayed at checkout in your currency once your address has been entered.

Frequently asked questions

6 questions

6 key questions

Up to what pH does EDDHA iron remain active?

How much EDDHA iron is needed for 1,000 litres?

The most widely quoted benchmark in aquaponics is an addition of about 2 mg of iron per litre roughly every 3 weeks, which is 33 g per 1,000 litres with a product containing 6% iron. Here is how to proceed:

Measure the dissolved iron. Below 1.5 mg per litre, the deficiency is established.
Weigh out 33 g, which adds 2 mg of iron per litre. If the test still reads about 1 mg per litre, 20 g is enough, as it adds 1.2.
Dissolve the powder in half a litre of warm water, stirring until the grains disappear.
Pour it into the tank or reservoir with the pump running, to distribute the product.
Measure again after 24 to 48 hours. The target is between 2 and 3 mg per litre.

Why does my water turn red after adding it?

Because that is the colour of the dissolved product. The iron-EDDHA complex is cherry red in solution: the tint appears within a few minutes and fades over a few days, as the iron is taken up by the plants. It is not precipitation, nor a reaction with the water, nor an algal bloom.

If the look of the water matters, in an ornamental aquarium or a very visible pond, DTPA 11% supplies the same iron without colouring the water.

Is EDDHA chelated iron harmful to fish?

No, it is safe. The reference dose of 33 g in 1,000 litres brings the water to 33 mg of product per litre, which is 2 mg of iron, whereas the ecotoxicity benchmarks for rainbow trout and for daphnia lie above 100 mg per litre.

Dose according to the volume of water actually in circulation, grow beds included, and not the nominal volume of the tanks. The product does not change the pH and does not harm the bacteria in the biofilter.

Can it be used as a foliar spray?

Yes, at 1 to 2 g per litre of spray solution, applied to the foliage. Foliar application bypasses the question of the water's pH, since the iron no longer has to pass through the roots: it is the quickest response on a plant that is already chlorotic.

As it does not correct the cause, repeat it for as long as the water pH stays high. Spray early or late in the day, never in full sun, and wet the underside of the leaves too.

Does the product affect the water pH?

How much EDDHA iron for your water volume

Enter the volume of water actually circulating in your system, including grow beds and reservoir. The calculation applies the reference dose of 33 g per 1,000 litres, which adds 2 mg of iron per litre.

System water volume

50 L5000 L

Reference dose, about every 3 weeks, to be dissolved and then poured in with the pump running.

Reduced dose, which adds 1.2 mg per litre, if the test still reads about 1 mg

0 g

The most widely quoted guideline in aquaponics is a dose of about 2 mg of chelated iron per litre roughly every 3 weeks. With 6% iron, you need 33 g of product for 1,000 litres, whereas 20 g adds only 1.2 mg per litre. Measure the dissolved iron before dosing and again 24 to 48 hours afterwards, because plant uptake and chelate breakdown between doses vary from one system to another: it is this measurement that sets the dose.

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Chelated iron (iron chelate) EDDHA 6%

The summary