I have the DIY version and you can't leave out certain elements. Leaving out one, leaves out many.I'm not talking about powdered AFR mix, I'm talking about the separate components that make up AFR. There is a "DIY recipe" that TM published before the powdered mix came out.
You can add or leave out anything you want that way.
I like the all in one approach for the big 3 so I can use a single dosing pump.
The DIY version has carbocalcium (alkalinity and calcium), bio magnesium (magnesium), and then trace elements A- and K+.
Pro-Coral A- Trace 2 Contains:
Bromine
Fluorine
Iodine
Lithium
Molybdenum
Selenium
Vanadium
Pro-Coral K+ Trace 1 Contains:
Barium
Boron
Chrome
Cobalt
Iron
Copper
Manganese
Nickel
Strontium
Zinc
You can't control the amount of each trace element. If you alter the recipe, you alter the amounts of many of the trace elements.
This may or may not work for your particular setup. You could certainly try it. My experience with AFR says your levels will be off and you'll be dosing individual elements anyway