Has anybody prepared Fe-EDTA?

jamesvladSeptember 25, 2010

Hello everyone. I some question about Fe-EDTA. I've prepared a solution of Fe-EDTA mixing two solutions:

1 - Disodium EDTA with sodium hydroxide

2 - Ferrous sulphate (with some sulfuric acid to dissolve completely the ferrous sulphate)

After mixing, the pH was adjusted to pH = 5.5

The result was a pale yellow solution.

After three days the solution changed its color to orange.

No precipitates.

So, my question is: Why the color of the solution changed?

Is OK to use this solution in hydroponics?

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danielfp

Hello James,

What happened is that some of the Iron (II) EDTA complex (which is yellow) oxidized to Iron (III) EDTA which is reddish giving your solution an orange tone. There is no need to worry, you can still use this solution in your hydroponic setup,

Best regards,

Daniel

Here is a link that might be useful: Science in Hydroponics

    Bookmark   September 25, 2010 at 10:22AM
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jamesvlad

Thanks danielfp. Now I am calm. Definitely I�ll use it because for me is cheaper to prepare Fe-EDTA than buying it.

    Bookmark   September 28, 2010 at 4:56PM
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sundarms74

frnds, i am new to hydroponics from india.i have got edta-Na and ferrous sulfate.can u specify the quantity of each to be added and exact method of preparing iron chelate solution

    Bookmark   January 5, 2014 at 12:20AM
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PupillaCharites(FL 9a)

The directions are very clearly stated in your thread history. Please study them until they make sense. For the amounts, you need to provide that depending on how much you are making, and you do this keeping the stoichiometry of the ferrous compound you are dissolving plus a minor excess. There is no magic concentration of trace EDTA so within reason you can make whatever concentration you want.

If you need more guidance, just use common sense. The n-sodium chelate needs to be unzipped. So using a hydroxide base bring it to a pH of at least 9, but I'd be careful not to get too close to 10 because you'll just be dumping in extra sodium, if using NaOH as suggested, and eventually wasting acid to neutralize it. In the acidified ferrous solution half, just enough to dissolve the final total needs of total liters at your working solution ppm of Fe ion you need and little more. If you add more you will have a solution with excess iron and you might have to keep track of the undependable free ferrous ions floating around too so that your fertilizer will be soluble Fe total = Fe(tot) = (free ionic + chelated ionic) with uncertainty.

After mixing, any pH at 6 or below is fine or even below 3-4 if you want a concentrated stock. The guy here used 5.5 which is a little more acidic than most normal applications, but that's like a pleasant visit to the chiropractor to massage the chelates into shape. I personally, if running at low pH of 5.5 would just dump some plain EDTA salt in my initial tap water which is around pH=8, and use straight ferrous sulfate added with the acid during the final pH adjustment, without all the extra work, but it is better you do it the way explained here, because what I suggest could behave a little fickly.

Don't abscond on us; post on what you are doing. It's real nice to hear from India.

This post was edited by PupillaCharites on Sun, Jan 5, 14 at 1:49

    Bookmark   January 5, 2014 at 1:05AM
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sundarms74

sure pupilla but u told the details r available in the thread.couldnot find any.i am not well versed in blogs and forums

    Bookmark   January 5, 2014 at 7:35AM
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PupillaCharites(FL 9a)

OK Sundar. I'm trying to help you. The difficulty I had with your question is the lack of detail also. You didn't mention what ppm you wanted for the final solution of chelated iron, nor how much you wanted to make, but you asked us to specify the exact amounts needed.

Whatever you need to know, just ask then. In which region are you planning to grow and with what type of hydroponic system and crop?

    Bookmark   January 5, 2014 at 10:54AM
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robert_1943

I have been doing hydroponic gardening for over 40 years and apart from the early years eg 30 years ago where I bought and mixed the nutrients together in large containers it was a real pain in the rear end..
I also did not have a PH meter until several years ago and a nutrient EC meter. Hydroponic gardening is fun and with the off the shelf nutrients and there are dozens of these to choose from, it is hard to understand how difficult we try to make hydroponics work. My rule of thumb is if the plants are growing okay dont mess it up, use the KISS principle and enjoy the journey of discovering the do's and dont's .One of my latest adventures is the Kratky method , raft, or still method, no pumps no electricity, just fill with nutrients and walk away until the plants are ready to harvest.Simple and easy. I will continue the other forms of hydroponics flood and drain, drip system, and the Kratky method, who knows I may even advance to Aquaponics, but in all instances I will keep it simple and fun.

    Bookmark   January 5, 2014 at 7:10PM
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sundarms74

It is a terrace garden.plan to grow brinjal, ladies finger and tomato.i am trying to prepare a solution based on kratky specifications, will get back finfing out the ppm of chelated iron solution I need.as I told I am from southindia and here we have a hot climate

    Bookmark   January 8, 2014 at 12:51PM
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PupillaCharites(FL 9a)

OK, if I understand you then want to use a typical lettuce Kratky recipe for a 'terrace garden' I'm honestly not sure what a terrace garden is but it sounds to me like non-recycling solution. Maybe in your part of the world this is more common but because I don't know, I can't try to comment on the specific application you have. Expect iron ppm to be something approximately from 1 ppm (parts per million) to 3 ppm, though. Thanks for clarifying the region, as you say, south India is mostly tropical. When I visited Shimla, N. India, though, I froze my knickers off.

    Bookmark   January 8, 2014 at 2:21PM
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robert_1943

Hello my friend in India, I have lived in India and understand the weather and the seasons you have.
There is no need to worry about heat as we in Australia have had 40C this week and I am running three systems which are working well. The terrace system I assume is the non recirculating method ( please correct me if I am wrong) .
If this is the case I am also growing all this items , but in the case of non recirculating I am only growing Brinjal ( Egg plant Aubergine) and is doing extremely well I am growing in a PH range of 6.5. to 7.00 and an EC range of 1.8 to 2.00 and they are throwing out growth and new roots are are very healthy. If you are using a drip system or flood and drain system please let me know as this can be a little different.

    Bookmark   January 8, 2014 at 7:21PM
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sundarms74

Sure Robert I will share updates.i also learned from net that the nutrient solution temperature is important better to jeep it around 25*C.is it essential to maintain that r nutrient solution can used in room temperature.i am olanning for a recirculating system only.will the temperature matter for a recirculating r non recirculsting

    Bookmark   January 9, 2014 at 2:15AM
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robert_1943

Hi Sundarms it really is good to know that someone in India is on this web site, as mentioned I have lived in North and South India and understand the temperature ranges plus the monsoon season and the blazing hot seasons.
I mentioned in an earlier posting that I live in Queensland Australia which also has its cyclone hot wet and dry seasons , fortunately we do do not have very cold seasons so we can grow all year long but being mindful of the seasons of what is the best crop to grow.
We have had a very dry season and hot, but in the last week we experienced the introduction of our wet season which started with temperatures getting to 40C (111.1F) this week and now with torrential downpours of rain.
I mention all this , as I have a flood and drain, with a 200 litre reservoir of nutrients, which I do not cool,nor do I have bubblers or aerators. I have attached a photo with a mixed group of plants some near maturity and some newer sowings ( Including seedlings planted yesterday) I am growing these plants outside under the roof eaves, and only on very hot days do I put a mesh to cover, ( PS I did not this week with the heat wave). I suggest with the heavy torrential rain that you may consider a covering or block screen out to cover all contingencies, but still allowing the UV and sunlight to allow normal growth.
I look forward to returning to India in the near future.
Please keep us posted and any photos as these are better than a thousand words.

    Bookmark   January 9, 2014 at 5:57PM
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robert_1943

Hi Sundarms it really is good to know that someone in India is on this web site, as mentioned I have lived in North and South India and understand the temperature ranges plus the monsoon season and the blazing hot seasons.
I mentioned in an earlier posting that I live in Queensland Australia which also has its cyclone hot wet and dry seasons , fortunately we do do not have very cold seasons so we can grow all year long but being mindful of the seasons of what is the best crop to grow.
We have had a very dry season and hot, but in the last week we experienced the introduction of our wet season which started with temperatures getting to 40C (111.1F) this week and now with torrential downpours of rain.
I mention all this , as I have a flood and drain, with a 200 litre reservoir of nutrients, which I do not cool,nor do I have bubblers or aerators. I have attached a photo with a mixed group of plants some near maturity and some newer sowings ( Including seedlings planted yesterday) I am growing these plants outside under the roof eaves, and only on very hot days do I put a mesh to cover, ( PS I did not this week with the heat wave). I suggest with the heavy torrential rain that you may consider a covering or block screen out to cover all contingencies, but still allowing the UV and sunlight to allow normal growth.
I look forward to returning to India in the near future.
Please keep us posted and any photos as these are better than a thousand words.

This post was edited by Robert.1943 on Thu, Jan 9, 14 at 18:01

    Bookmark   January 9, 2014 at 5:59PM
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robert_1943

Sorry guys I duplicated this posting and cannot delete

    Bookmark   January 9, 2014 at 6:06PM
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sundarms74

Hi guys atlast I found a way out to prepare my own FeEDTA in10X strength in ppm it comes around 2.7 I think.i have got my nutrient stock solutions prepared.i have got my 4inch pvc tube holes drilled.i am about to mount.i have started germinating tomato nd ladiesfinger seeds.now I have ten netpots.i plan to use cocopeat and gravel as grow medium.i plan to have DWC and NFT.i want the forum to guide me the amount of nutrient solutions for these and frequency of watering.

    Bookmark   January 18, 2014 at 4:44AM
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robert_1943

Pupilla Charites you are the one fully conversant with chemicals maybe you can answer sundarms request.
I grow my plants as mentioned by sundarms at a ph between 6.5 and 7. and an EC between 1.6 and 2. I water my expanded clay with the ebb and flow method at about every every hour during the day for fifteen minutes and more frequently when it is very hot, during the night only once. My drip system also using expanded clay I have found 30 minutes on 30 minutes off.Using coco peat will retain moisture longer, but I would suggest trial and error to find a suitable time as temperature has a large amount of what time is suitable so your plants do not stress. Pupilla Charites this is your area of expertise .

    Bookmark   January 18, 2014 at 8:14PM
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robert_1943

Nutrient (salt) concentration are measured by their ability to conduct electricity through a solution. Dissolved ionic salts create electrical current in solution. The main constituent of hydroponic solutions is ionic salts. Several scales are currently used to measure how much electricity is conducted by nutrients including: Electrical Conductivity (EC), Conductivity Factor (CF), Parts Per Million (ppm), Total Dissolved Solids (TDS), and Dissolved Solids (DS). Most American growers use ppm to measure overall fertilizer concentration. European, Australian, and New Zeland growers use EC, however they still use CF in parts of Australia and New Zeland. Parts per million is not as accurate or consistant as EC to measure nutrient solution strength.

    Bookmark   January 18, 2014 at 8:29PM
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PupillaCharites(FL 9a)

Hi Robert and Sundar,

Thanks Robert! I'd like to help him but to be honest I think you did better than I could already with your EC ranges (if anything I prefer pH 6-6.5, but I don't touch it until it gets above 6.9 or so or below 5.8, preferring to let the system gradually change since my personal way is to avoid any adjustments until they become essential. I can add that about 7 grams solid pure fertilizer (not including water in solutions, only the solid they deliver) per each 4 liters will put you in the middle of Robert's perfect EC range and if you don't have a particular solution and are making your own, you can start with a basic Hoagland solution, which is a generic good formula for tomatoes that has been around since the beginning of modern plasticulture hydroponics. For the iron specifically 2.7 ppm sound good to me as it is slightly higher than some other veggies. Tomatoes have a somewhat higher iron requirement so a good ballpark for most of the time is about 3ppm of chelated elemental Fe.

As for frequency of watering, I don't use organic media like cocopeat since I got a wheelbarrow full of hydroton type baked clay, perlite and vermiculite taking up my limited storage space, so best to listen to Robert and others on that, but as he says, 15 minutes every hour is way to much IMO. good luck

    Bookmark   January 19, 2014 at 1:08AM
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sundarms74

thank you roberts and pupilla for your feedback.i have already placed order for pH kits.i want to know whether it is enough if i go by pH alone r i should check EC and TDS and all.i have added an image of my NFT setup.

    Bookmark   January 20, 2014 at 1:16PM
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PupillaCharites(FL 9a)

Thats good that you can manage pH soon. I measure three things: pH, EC, and temperature. Once I decide on my fertilizer solution concentrations and can make the solution, I don't give the EC very much attention unless there has been a rain, and by using the EC I can confirm how much rain fell into the solution, but this is just fun to do and not essential for me.

At the moment where I live it is cool weather and I do not have much evaporation of water from the solution. Today was the warmest day, at a high of 19C! Warm!

On the other hand in someplace like Mysore,19C will be the humid night low temperature, but you may be a very dry 32C in the afternoon when your relative humidity can easily fall to 32% - which is a warm desert situation. At that time there will be a lot of general evaporation and transpiration of water into the air from the plants. So you will need to be sure your total solution stays a same volume of water, or the nutrients will concentrate a lot if too much water is lost into the air. That is nothing I am worried about, but your weather probably presents that situation. An EC meter can be very helpful to know for sure what is happening, but if it is difficult or expensive to get one, you can do without it as long as you start with the right fertilizer strength (and not too hard water, or not too salty if close to the coast), which will depend on your source preparation of water, and you regularly add water (or allow rain to fall in like I do) to the solution as it is lost by evaporation to maintain the same volume.

Finally, to do without an EC meter another tip is to have at least 2.5 liters per plant for light feeders and 5-6 liters per plant for heavy feeders. This will insure a larger reservoir of fertilizer is always available and it will attenuate fluctuation of EC during the cycle. You can keep it longer before changing too, which is more convenient ;)

    Bookmark   January 20, 2014 at 2:32PM
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professionaladvice

Fe-EDTA is the worst of the three choices for a chelated iron micro-nutrient supplement when growing anything hydroponically. It is not stable at the pH range that hydroponic nutrient solution must maintain to keep a happy median balance for all the different elements to be as soluble as possible without locking any particular element out completely.
Forget FE-EDTA in water culture unless you plan on a pH range that is uncommon for hydroponics.
You may use Fe- DTPA or Fe-EDDHA. Don't take my word for it, scour the net for sources of corroborative evidence to support my claim. One such source is the product literature for the various Sprint (brand name) Fe chelate powders.
Fe-DTPA is all you need but you could also use Fe-EDDHA but it will cost slightly more. Although, Fe-EDDHA is flatline stable across a very wide pH range.

    Bookmark   January 27, 2014 at 2:29PM
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