I'm having sand in the cooked amaranth and teff if the package has some in it. Is there a way, how to filter it out before cooking it? Or I just need to find a proper brand?
If the sand is significantly smaller than the grains, rinse the grain in an appropriately sized sieve. If the sand is denser than the grain, perhaps the grain would float and the sand would sink in a large amount of water?
If neither of those ideas work, then you may need to find another brand.