I know it sounds terrible, but it works great because it's natural food for them. Remember that corys produce very tiny fry and they live on the bottom, and it will all start to make sense. They are different from livebearers or other egg laying fish whose young swim higher in the water.
You will also be doing daily partial water changes to keep the water fresh, and the gook that settles on the bottom will gradually be removed as you go along.
You will also be doing daily partial water changes to keep the water fresh, and the gook that settles on the bottom will gradually be removed as you go along.