So Korallen Zucht's Zeovit product line has been around for a while. It contains many products, but one that finds usefulness outside of the ultra low nutrient setups is Coral Snow. In addition, the claims that KZ makes about it are not completely absurd and actually lie in the science of it. They claim it is a 'calcium-magnesium carbonate mix' (aka MgCO3 and CaCO3). When dried, it looks like an off-white confectioners sugar, extremely fine ground powder.
It is essentially a calcite chalk. Yes, the same stuff that teachers used to write on chalkboards with, that is bought for pennies and sold in RO/DI at nearly $120 per liter.
Despite being expensive, it does have its benefits. Organics adhere to its surface, as do particulates, acting as a flocculent, being easily removed via protein skimming or small micron mechanical filtration. This leads to unparalleled water clarity.
Thankfully there is a cheaper way to get that same clarifying effect. You can purchase food grade calcium carbonate powder, minimum 97% purity, for around $9 per pound, less if you order more (but that's not really necessary).
It comes as a very fine powder. You will want to mix it with water before dosing. The amount of KZ product in each mL (after it is very well-shaken to thoroughly mix) is 0.4g. This is a bit less than 1/8 teaspoon, and this is good for roughly 100 liters aquarium volume (25 gallons). You can either just put the dry powder into a small container and mix right there, or you can create a stock solution.
For a 250mL solution, use 5 level tablespoons (roughly 115 grams) of CaCO3 powder and add roughly 230mL of RO/DI water. This should mix right about 250mL. The powder will NOT dissolve, it will stay suspended in the water. Will look like this when you're done.
