Backyard Aquaponics
A place to discuss aquaponics

I have seen "Maxicrop plus Iron" mentioned a number of times to help with some nutrient deficiencies so I decided to purchase some from Amazon.

I was alarmed when I saw this on the back though!



"Not Intended for use on food crop sites."

Is that something I need to worry about??

Not sure what's going on there. Looks like they added a sticker, my bottle doesn't have that although it doesn't list a garden use, blueberries are acid loving and produce fruit. This site lists it for gardens but it may just be a cut and paste type of thing - http://www.arbico-organics.com/product/liquid-seaweed-iron/organic-soil-conditioners

The analysis is here along with the Washington State standards for metals (which are based on Canada's since they did a 45 year study on metals accumulation in soils (click the link near the metals standards, it starts with WAC for more about that) - http://agr.wa.gov/PestFert/Fertilizers/FertDB/prodinfo.aspx?pname=6759. Don't take my word for this but I believe the product has to fall below the metal standards to be listed as a commercial fertilizer (keep in mind that the application rate factors into this, it isn't just the analysis).

You can look at the analysis of a few of their other products which are designated for garden use from here to compare - http://agr.wa.gov/PestFert/Fertilizers/FertDB/suppinfo.aspx?pname=2351
You might also want to check on other seaweed products but again the usage rates matter.

This might be a Canada issue and some regulation there

I noticed that the company had some expired analysis information as I looked at a few of the chemical analysis sites.

I also noticed their OMRI cert that they have posted on their website for their seaweed powder expired in Dec 2014 - http://www.maxicrop.com/PDFs/MAX_OMRI_2014.pdf Not sure if they just aren't keeping up with their web page, decided not to mess with OMRI or what

..
CHLORINE... not more than 1%

Although seriously diluted when added to a AP system, I do wonder about Chlorine.. any chlorine..
..
.

At normal dose rates I wouldn't worry about the chlorine, even if it was an aquarium system a couple of tablespoons won't hurt anything.

Just from reading were this comes from, should tell you not to buy it.

There description is far-fetched, especially 12,500 miles of coastline.

Besides the iron doesn't come from the seaweed, it was added using Ferrous Sulfate.

Just find Ferrous Sulfite and make your own.

As for the Chlorine, open the cap and let it off-gas for a few days.

The chlorine is probably there to prevent the growth of Iron bacteria and I wouldn't be concerned about it at these amounts either.

Could it be the salt content of the seaweed? Ongoing use in a field might make the salt levels in the ground too high?

Very likely now that you mention it Colum. The use of chlorine instead of chloride through me - Their test probably registers it as chlorine but it's probably chlorine in the form of chloride.