Backyard Aquaponics
A place to discuss aquaponics

I have 3 aquaponics systems 1 big and 2 small. I have recently put some herbs in all of them and the leafs are going yellow and ends of leaves look slightly burnt so I think it might be Iron Deficiency.

Should I buy Chelated Iron powder and put some in the grow beds.

If so how much should I be looking to spend on the powder (I don't want to spend much) and how much should I put in???

Also, can the Iron be harmful to my fish (tilapia and goldfish) in anyway???

Thanks for your help.

Chelates iron EDDHA,best place could very well be ebay in the uk,good place to start. I believe foliar feeding will give you a quicker response,system dosing,the Rakocys standard is 2milligams per litr of water,EDDHA is 6% so 33 milligrams per litre, dosed in the fish tank. This is a lot,so its a case of dosing just enough to keep the plants happy without wasting money by over dosing,but at least you know this is the max upper limit for dosing, try to keep away from EDTA it's toxic.
Iam a newbie to this myself and I have just posted under Plants a PDF describing plant deficiencies,could be just want you want.

I just paid about $50 USD shipped for 5lb bag of Sprint 330 on ebay which was the best price I could find.

Yep that is DTPA which is also good

I just purchased EDDHA from Bangkok, 480 Baht a kilo,min order 10 kilos,works out best part of £100. That made me swallow hard,at the correct dosing level I need about 400 grammes every three weeks.....

Quote " Plants uptake iron in its oxidized forms, Fe2+ (ferrous form) or Fe3+ (ferric form).

Plants use various iron uptake mechanisms. One of these is the chelation mechanism - the plant releases compounds called siderophores which bind iron and enhance its solubility. This mechanism also involves bacteria.

Another mechanism involves the release of protons (H+) and reductants by the plant roots, to lower pH levels in root zone. The result is increased iron solubility.

In this respect, choice of the form of nitrogen fertilizer is significant. Ammonium nitrogen increases proton release by roots, thus lowering pH and facilitating iron uptake.

Nitrate nitrogen enhances the release of hydroxide ions that increase pH in the root zone and counteract efficient iron uptake.

New roots and root hairs are more active in iron uptake, therefore it is imperative to maintain a healthy active root system. Any factor interfering with root development interferes with iron uptake.


Managing Iron Deficiencies
When iron deficiency is identified, it can be treated in the short term by applying a foliar spray of iron, but the best course of action is of course prevention. Therefore, the grower should identify the real cause of the deficiency and treat it, in order to prevent the problem from occurring in the future.

Often, iron deficiency does not indicate insufficient iron supply. It may also be related to various conditions that may affect iron availability. For example: carbonate levels in the soil, salinity, soil moisture, low temperature, concentration of other elements (e.g. competitive microelements, phosphorus, calcium) etc.

Evaluating these factors and correcting them can save a great deal of money spent on ineffective and unnecessary iron applications.


Iron Fertilizers
Iron can be applied as ferrous sulfate or in a chelated form.

Ferrous sulfate (FeSO4) contains about 20% iron. This fertilizer is inexpensive and is mainly used for foliar spraying. Applied to soil, it is often ineffective, especially in pH above 7.0, because its iron quickly transforms to Fe3+ and precipitates as one of the iron oxides.

Iron chelates. Chelates are compounds that stabilize metal ions (in this case - iron) and protect them from oxidation and precipitation. Iron chelates consist of three components:
Fe3+ ions
A complex, such as EDTA, DTPA, EDDHA, amino acids, humic-fluivic acids, citrate.
Sodium (Na+) or ammonium (NH4+) ions
Different chelates hold iron ions in different strengths at different pH levels. They also defer in their susceptibility to iron replacement by competitive ions. For example, at high concentrations, calcium or magnesium ions may replace the chelated metal ion.

Fe-EDTA - This iron chelate is stable at pH below 6.0. Above pH of 6.5, nearly 50% of the iron is unavailable. Therefore this chelate is ineffective in alkaline soils. This chelate also has high affinity to calcium, so it is advised not to use it in calcium-rich soils or water.

Note that EDTA is a very stable chelate of micro-elements, other than iron, even in high pH levels.

Fe-DTPA - this iron chelate is stable in pH levels of up to 7.0, and is not as susceptible to iron replacement by calcium.

Fe-EDDHA - this chelate is stable at pH levels as high as 11.0, but it is also the most expensive iron chelate available.




In soilless media and hydroponics, pH monitoring of water and media is relatively easier than in soils. When regular testing is performed, and pH control is adequate, it is possible to prefer the inexpensive, less stable iron chelates.

On the other hand, in alkaline soils, where it is difficult to effectively decrease pH levels, it is advised to use more stable iron chelates, such as EDDHA. " end quote.

My system is showing a very slight iron defficincy, so I was googling around klooking for a mixing ratio for EDDHA as a foliar application,when I came across this. There is always questions concerning iron and iron defficincy, so I copied this and shared it here,hope it helps .

Nate gives a run down on all the forms of chelates here

https://www.youtube.com/watch?v=E4_hCAnymFw

Thanks Mantis, very interesting link.

I have always used the Searls Chelated Iron which is Fe EDTA. (most likely ineffective in many AP circumstances)

I'm now madly looking for a local source of either Fe DTPA or Fe EDDHA, that's my mission for this week.

I just bought some iron chelate, unfortunate it was searles EDTA.

Yates make it as well but on the web I can't see if it is EDTA or DTPA?

Burnt tips isn't usually iron deficiency. Most likely not enough potassium or maybe too much calcium in your system. What buffers or hydroxides do you use? Shell grit, egg shells, hydrated lime, KOH?

Slowboat:

It's EDTA, I questioned that with Yates on eBay, here's their answer.



This particular one is an EDTA. Sorry we can't be of help to you and I hope you find the type you're after soon.

Cheers

Best Regards

yates_gardening


http://msds.duluxgroup.com/pdf/shess-en ... 020597.pdf

Yeah - I've been looking for a non EDTA form in Oz and have not found one as yet.

Interesting to know about its in effectiveness at high ph and wth high calcium - Probably the likely conditions when it would be needed in a AP system!

Iron addition is required in all AP systems as it isnt formulated into feed and alike.

Thanks Joblow, the only suitable stuff I have found in Oz is from this mob.

manutec make it, but they also make the EDTA type as well.

http://www.greenfingers.com.au/store/?4 ... ag-sampler

Is your system REALLY HUGE?
Just wondering since I was always under the impression that iron chelate was added in much smaller quantities?