The second is an algae of Rhodophyta. I don't know what it is (or it may be Phaeophyta), but it is definitely edible.

The third kind is ice algae (Gracilaria lemaneiformis)

These three species are all edible algae.

There is not much economic value.

You hoard too much.

It is normal that sales are not good.

Here are some suggestions:

1 Looking for an export company. They are interested in seaweed.

Export long-term acquisitions abroad to Japan, South Korea and Western Europe.

Duck and chicken are used as feed. The eggs laid by ducks and chickens fed with this seaweed are of good quality and can be mixed with chicken feed and sea red.

This is a bad thing. Note that D is buried as fertilizer.

That's all I know