Some Possibly Controversial Questions About Micronutrients

I've been re-evaluating my stock dry fertilizers and I think I am shying away from Plantex CSM+B and more towards Miller's Microplex, so I'll start with the easy, non controversial question:

If I am using PPS-Pro which recommends 80 grams per liter of Plantex CSM+B, what would be the recommended amount if I switched to Miller's Microplex? I have feeling this involves looking at the guaranteed analysis and doing some good old fashioned math but I hope I can spare myself the trouble and see if someone has figured this out already.

Now, the controversial bits:

Have we been too quick to embrace Plantex CSM+B? Have we been accidentally taken for a ride? Don't parse that as merely being inflammatory, let me explain.

There are a couple of threads around here that compared the ingredients and their concentrations of both Plantex CSM+B and Miller's Microplex. One had a little more of this than the other and one had a little less of that than the other, in the grand scheme of things it was probably a wash but I recently thought of something.

Recently, as in the 1970's, it was determined that Nickel is an important micronutrient. It was never a major concern because it is quite abundant in the Earth's crust and is easily deposited by the action of wind and rain. In fact it took a few generations of wheat and rye grown in an almost sterile environment to deplete the nickel in a test plot before a nickel deficiency could even be observed and studied but then, plants only need precious little, about 80 nanograms per gram maximum. It turns out it is pretty important to plant fertility, namely seed viability and yield and also appears to make nitrogen metabolism more efficient. Again, its superabundance on Earth doesn't make it much of a concern like carbon, hydrogen, oxygen and sulfur.

Then it hit me all of the sudden, I don't grow my plants in plots outside and nor do I use soil (something I'm on the verge of changing anyway). I don't know that nickel exists in my substrates of choice. I can't say for sure if it is in the potting soil that we like to make our mineralized topsoil from. It appears absent in every other commercial aquarium fertilizer except for Seachem Flourish which has a whopping .0000036% (36 ten millionths of a percent) which is 4,500 times more nickel than any plant needs if I have my math right. It's also in Miller's Microplex. Their registration with the Washington Dept. of Agriculture shows it to have 1 ppm of nickel. If we do the conversion assuming they do mean 1 mg/L of Nickel then that works out to 12,500,000 times the nickel recommended for healthy plant growth. I have a feeling I'm not getting how this guaranteed analysis thing works and I understand its a pretty flawed way to list the components of a fertilizer anyway.

My other concern is Cobalt. This one is vitally important for shoot development and thus ethylene synthesis which drives that process. This is of more importance to terrestrial plants but to complete their life cycle the vast majority of our water weeds need to grow out of the water where the presence of ethylene would really matter a lot. I noticed that cobalt is conspicuous by its absence in Plantex CSM+B but present in Miller's Microplex and once more in Seachem Flourish.

Are these really that important? They sound like it to me from what I've read so far. Am I making much ado about nothing? Is it perhaps good to consider but not fret over because perhaps they do make it in our tanks one way or another? What do ya'll think?

I have a feeling this may require the brain of Tom Barr as I feel myself rapidly falling out of my depth...