Some Brightwell products are likely just fine. Others seem poorly thought out, from a scientific standpoint (although a cynic would say the point is sales, not utility).
Here are some of my thoughts on them:
Liquid reef is like Purple Up or Kent Liquid reactor in that the main ingredient (fine sand) does not dissolve in seawater. I do not recommend it.
Kalk +2 is also poorly thought out. The magnesium in it does not dissolve in limewater. And there is very little present anyway.
Their iodine product claims that iodide is the primary iodine-containing ion in seawater, which is incorrect.
Another Brightwell product that I have a problem with: "elemental". Specifically, I can't imagine anyone choosing this odd mix of things even if it worked as described, which it won't.
You can't link right to it, but it claims to have the useless aragonite, like Liquid Reef, but then goes on to add additional calcium and strontium, and a miniscule amount of magnesium.
If it worked as claimed, it is a very odd and unbalanced mixture of calcium and alkalinity. Since the aragonite won't dissolve, it is basically like a mixture of calcium and strontium, along with a miniscule amount of magnesium and potassium.
What would one use that for? The text says as an add on to other methods to diversify additions? That is a goal???