No. Sodium selenite is an inorganic salt with the formula Na2SeO3 containing the elements sodium alginate supplier - https://ingreland.com/products/sodium-alginate-supplier/ , selenium, and oxygen. Sodium alginate is an organic ionic polymer containing the elements sodium, carbon, hydrogen, and oxygen. They are two completely different compounds - https://de.bab.la/woerterbuch/englisch-deutsch/compounds .