Heres the problem!

After experiencing what appeared to be an iron deficiency I began adding MircobeLift Iron Cheate 60ml at a time.   The levels would come up slightly, and then drop out of sight and the plants were not looking any better.  When I began to run out of MicrobeLift I shopped locally and found Dr Iron which boasted 8% iron chelate.   I had my doubts and so I tested the strength of two iron chelate products.  MicrobLift does not specify the percent and I think I know why.  Heres the results and my method of conducting the test.


I started with 0.5 ml
added 200 ml of distilled water
this gives me a dilution of 0.5/(200+1) = 0.00249

then taking my next sample from this dilution, I repeated the procedure resulting in a 0.00000622 dilution.

Assuming the product is 8% FE+ as claimed then two dilutions results in 0.5 parts per million which is mid scale on the FE test.

Here are the results of testing equal amounts of both MicrobeLift and Dr. Iron

This first picture shows the Iron  and the second shows the Chelate Iron

Dr. Iron = 0.25 ppm

MicrobeLift = 0.0 ppm

Dr. Iron => 1.0 ppm

MicrobeLift = 0.0 ppm

I tested a stronger sample of Microbelift and verified a trace amount of Iron Chelate, but Dr. Iron is less expensive for more product and provides a substantially more concentrated dose of iron chelate .  In fact Dr Iron contains over twice as much Iron Chelate as they advertize! But its in the form of EDTA which requires a low pH.

MaxiCrop Seaweed with Iron claims 2% iron chelate and is a favorite among other aquaponic enthusiast, but I did not test that product. 

Here are the real world results.    In the weeks ahead of switching to Dr Iron I had applied 1-1/2 bottles of MicrobeLift with meager results.  Two days after using just a small amount of Dr Iron the plants have begun to show obvious and rapid improvement.

MircobeLift

Dr. Iron  2012-06-23_1731

Dr Iron 2012-06-24_1810

I have continued to add 25ml of Dr Iron to the 1000 gallon system once per day and when I add the iron I pour it directly on the Hydroton as I did with the MicrobeLift.

Update:
Today is Tuesday June 26 2012.
This mornings test showed that the level of chelated iron was nearly the same as yesterday!  The chelated iron may be normalizing after only three days of dosing with Dr Iron as opposed to MicrobeLift.

While the two beds show a significant difference in growth, the raft system has become healthier and is showing a lot of promise.  The foliage has become green and the plants are beginning to grow again.

Dr Iron is a far superior product.  Im guessing MicrobeLift is making an effort to sell something that will not change the color the water in an aquarium.  But I think they should state the percent in order to be more honest about the product.

Dr Iron has caused my water to take on a brown color, but this is a aquaponic system not an aquarium so to really is not important.

The tomatoes have grown up around the basil since my last photo.  The basil on the left is from the raft. 

Look at how much the basil in the gravel has grown!

This is the basil in the raft.  It has regained most of its color and it doing much better since I switched to Dr Iron

The raft is clearly stunted and anemic, but I have hopes of a full recovery

Dr Iron is great, but it may not be available. So Ill address iron products in general.
This is from Green House Grower
There are many chelating molecules available, but only three that are commonly used in horticulture: EDTA, DTPA and EDDHA. These abbreviations refer to the chemical structure of the organic molecule. In general, manganese, zinc and copper chelates are only found in the EDTA form. In comparison, there are three forms of iron chelate, FeEDTA, FeDTPA and FeEDDHA, although the most common form is FeEDTA.
With iron nutrition, the form of iron is very important. The three common chelated forms (iron-EDDHA, DTPA and EDTA) differ in their ability to hold onto the iron (and therefore keep iron soluble and available to plants) as the media pH increases. Between a media pH of 4.0 to 5.5, any form of iron will work (including iron sulfate) at supplying iron to the plant. However, as the media pH increases above 7.0, only the iron from Iron-EDDHA has high solubility. Research has shown that the ranking of iron forms from most effective to least effective at supplying iron at high media pH is Iron-EDDHA > Iron-DTPA > Iron-EDTA > Iron sulfate. If iron is applied in a form that is not soluble because of high media pH, then most of the nutrient will not be available to plants until media pH is lowered.

In general the best products will say EDDHA because they work over the widest range of pH

This article at deseretnews.com may also help while shopping for an iron product
Other less-expensive products are also available. One widely sold product, Ironite, contains iron sulfate.
Holt explained Ironite has a "high sulfur content that helps to temporarily acidify the soil around the plants, so work it in around the plant, and then water it in. It works well on turf and on some plants if the soil pH is not too high."
"Another product we sell is called Dr. Iron," he said "It is 22 percent iron and 55 percent sulfur. It basically takes iron oxide and covers it with molten sulfur. As the sulfur dissolves, it releases the iron."
IronSul Soil Acidifier with Humic Acid is another way to treat chlorosis. It is acidic, so it lowers the pH, making the iron more available. It also has a small amount of zinc to supply that micronutrient.
Foliar sprays to the leaves often produce a quick response, but they are inconsistent and temporary.

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