What household products contain algae?

Fish Tanks or plants?

Examples of products that contain carrageenan are dog food, chocolate, toothpaste and baby food. Alginate comes from brown algae and is used to make water-based products thicker or creamier. Ranch dressing, heartburn relief medicine and hand creams all can contain alginate.

*Carrageenans or carrageenins are a family of linear sulfated polysaccharides that are extracted from red edible seaweeds. They are widely used in the food industry, for their gelling, thickening, and stabilizing properties. (Wiki)