Would this be a safe and effective fertilizer for phytoplankton?

Alfie Hayward

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Feb 21, 2019
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Hey, just wanted a second option on this fertilizer i have got. I am trying to grow phytoplankton to feed my rotifers to feed my clownfish fry. I know that F2 if the standard fertilizer phytoplankton, i have ordered some F2 but won't be getting here until the new year, and i was hoping to get started growing at the moment.

I picked up this "Organic Marine Phytoplankton Soil Enhancer" to try as a substitute for F2, I've read that miracle grow can be used but have heard story's of it not working out and i didn't like the ingredient list for it.
This stuff i have picked up has the following ingredient list:
Calcium: 420ppm
Magnesium: 1360ppm
Nitrogen: 1900ppm
Phosphorus: 9.6ppm
Potassium: 314ppm
Boron: 5.3ppm
Iron: 4.3ppm

Firstly would this be safe to use as a phytoplankton fertilizer, and second would this be effective for the time being.
Thanks for the help. :)
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Randy Holmes-Farley

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Arlington, Massachusetts, United States
I do not know what conditions are optimal for phyo culture, but let's look at what happens if you use it to, say, attain 0.1 ppm phosphate (0.03 ppm phosphorus) in 35 ppt seawater.

It contains 9.6 ppm phosphorus, so to get the results for other additions, we multiply by 0.03 ppm/9.6 ppm = 0.0031

I cannot tell what form the nitrogen is in the picture. It may not be nitrate. Might be something undesirable.

Nitrogen will be boosted to 0.0031 x 1900 ppm = 5.9 ppm N or 26 ppm nitrate equivalent. Seems OK if that is as nitrate

Iron will be boosted to 0.013 ppm. It's way above NSW, but may be fine.

Potassium is boosted from 400 ppm to 401 ppm. Not useful, but is fine. Same result applies to calcium and magnesium and boron.

So my only concern is what form of nitrogen is present.

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