Yeah it does feel a little like Alchemy, a little bit of this and a little bit of that, except it's in the pursuit of turning the elements into healthy plant tissue. I like to think I am helping to counteract the Magic that Bucephalandra use to do a vanishing act when they don't like what's on offer, this from a plant that supposedly thrives on thin gruel (Rainwater over Karst and roots in Interstitial Soils which are mainly composed of dead epiphytes). From what I have seen they appear to prefer their breakfast wrapped in a tasty pastry they can absorb for extra nutrition rather than have them offered it wrapped in a synthetic they can't absorb, and I fear if they do manage to tear up that synthetic wrapper and if it is Ethylene based could be a cause to trigger tissue loss wherever it was dismantled (ethylene in a plant is used as a signalling hormone to trigger cell death). Also I remember reading something somewhere (can't remember where) that one of the problems of using the wrong synthetic chelate for the pH range of the target element is that it could lead to unbound chelate being absorbed into the plant where it then chelates with something the plant wants to store and then robs it of nutrients if it gets transported back out the plant. As a consequence of the pH range I run at I'm keeping away from EDTA traces and only using a small amount of FeDTPA for Iron persistence day to day.
It's quite interesting to compare the size difference between the Humic and Fulvic Acid molecules. Shortcrust pastry or Puff pastry, I assume they both appear quite delicious from a plants perspective.
This is quite an interesting article -
Humates and Humic Acid. How do they work?
Commenting on the purity of the Humic and Fulvic Acid sources you found it might be worth comparing.
Here's the back label for the RAW brand Humic Acid source I mentioned above.
As you can see it's sourced from Leonardite and it is only 59% purity, so your 80% purity grade appears to be a more concentrated product, very likely it is from a locally sourced Leonardite deposit, the question you need to ask is how it was prepared, which hydroxide was used to solvate the Humic Acid, the RAW one above uses Potassium Hydroxide hence the 4% K content, other hydroxides that can be used are Sodium Hydroxide or Ammonium Hydroxide (from what I've read the Ammonium formulation smells pretty bad). I would prefer the Potassium based product simply because it's the preferred transport ion within plants, certainly more beneficial than Sodium. The Ammonium based product would probably have its uses for the nitrogen component and seeing that humates are used as soil conditioners I would not be surprised if prilled ADA type nutrated plant soils are fortified with this, so I reckon it's has a more targeted use wheras a Potassium based Humic Acid can be applied more liberally as a Tonic in an aquatic environment.
The RAW Full Up product doesn't state its Fulvic Acid content but it does state its Humic Acid content at 10%.
It is stated that it is sourced from Peat so the product should contain a high percentage of Fulvic Acid and other Humates (there's a multitude of different ones, Fulvic and Humic are the big two).
The 10% Humic Acid content is either what's left in the purification process or added purposefully as apparently the presence of Humic Acid can be seen to increase the uptake of Fulvic Acid, possibly because as the plant is uptaking the larger molecule it's holding the door wide open in places (like squeezing a square peg into a round hole, or vice versa) and as consequence the smaller molecules of Fulvic Acid can squeeze through the gaps. So the Fulvic source you found at 62% is likely a very similar product (maybe a different source), it will have other soluble Humates and possibly some undisclosed Humic Acid (don't know how rigorous centrifuging needs to be to separate precipitated Humic Acid from liquid containing Fulvic Acid to have a Zero level for Humic Acid). A combination of both is probably more desirable than Fulvic Acid on its own.
I can't be certain but I dont think there is much of a need to worry too much about harmful contaminants as the original source for these products (excepting possibly the type of Hydroxide pH moderator used to solvate the Humic Acid) as Peat and Leonardite are mainly composed of pre-fossilised plant derived organic matter, so if there are any undesirable contaminants present hopefully they will be at an extremely low level.
Certainly all this DIY malarkey is not for the everyone but I think where there is the absence of an easy to find nutrient source pre-made or one that comes with the required level of desired elements, then learning how to be able to tailor universal base ingredients together in a way to be advantageous to plant health has to be worth the effort.