System Test and micro nutrients

Going on our 4th year of aquaponics.

After running all year, with minimal freezing, it was time to test the levels.

Temp was cool in the mid to upper 60′s.

Most aquaponic systems once established require very little maintenance.  This is our very first reading of 2013.

This shows a 7.4 average reading for PH, 0-.10 for Ammonia, 0 Nitrite, and high Nitrate of close to 80ppm.

Why are the other two not showing, but yet plenty of Nitrates?  Simple, the readings on the scale aren’t sensitive enough to get down to the 0-.10 range for nitrite and ammonia.  I have found on the internet some test strips that do a very low ammonia testing.   The third and most important is nitrate, shows an over abundance of nitrates.

So then why do my strawberry’s look nitrate deficient?

This is also an example of a nitrate deficiency, BUT our nitrate reading above shows we have plenty?  What gives?

Lets take a closer look at the image.  The bottom older leave is dark green, while the newer growth is light green with dark green veins.


First we reference our resources, and find a link to deficiencies (this will be added to our app as time allows).

Iron or -FE is what we are deficient in.   This is probably one of the most common problems to any healthy aquaponics system.  We can resolve this by using iron chelate, or iron that is water soluble.  This is what most are recommending in the community to purchase.

We did find one problem with this Iron Chelate that no many people talk about.  On a small sticker on the side.  ”Warning: this product contains chemicals know to the State of California to cause cancer and birth defects or other reproductive harm.


Yup, here we find out Arsenic, Mercury, and even Lead are contained in this product.  You can always do a MSDS search on any product.


Check out this google spreadsheet for a breakdown.  Found through MSDS’ and university articles.  Google Spreadsheet Analysis 


—- chart with breakdown goes here — 

So what does this mean?


On the average, there is about 10-20 mg or 10-20,000,000 ppm of arsenic in the human body [source]

Maximum levels in drinking water is 0.010 [source]


Mercury:  Tuna fresh or frozen has 0.32 ppm, and Tuna canned has  .17ppm.

Also further research shows  on consumer reports.

  • Samples of white tuna had 0.217 to 0.774 ppm of mercury and averaged 0.427 ppm. By eating 2.5 ounces of any of the tested samples, a woman of childbearing age would exceed the daily mercury intake that the EPA considers safe.
  • Samples of light tuna had 0.018 to 0.176 ppm and averaged 0.071 ppm. At that average, a woman of childbearing age eating 2.5 ounces would get less than the EPA’s limit, but for about half the tested samples, eating 5 ounces would exceed the limit.


Total Mercury in Aquaculture Fish [Source]


The Toxicity of cadmium and resulting hazards for human health. [source]


Lead in soil is not particularly mobile; that is, it isn’t easily taken up by plant roots. [source]


Does our local water have any effect?

Nope, I found our local water provider “York Water” water analysis [here]


And for those of you still with me … here is an article from Sandford

Human Health Concerns of Lead, Mercury, Cadmium and Arsenic. [source]



So.. the jury is still out on this one, to add or not to add. That is the question.

This is going to require more research…. to be continued.


Updated 4/30/13 :  We decided to scrap our Iron Chelate, and AZomite due to other harmful trace elements (Cadmium, Lead, Mercury, and Arsenic).  We are now going for 

EDDHA Iron Chelate 6%.  It’s more expensive, but so far not a single trance element. 

We have contacted the company and are hoping for a better chemical analysis.

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