Some have added it, but it's really not needed near as I can tell.
I think in really productive systems, yes, but not here in the above tank, some of these are slower growing, a mass of Caulpera? Perhaps.

Sediment is just aragonite sand. Deep+ a little bit of marine mud from the Florida Keys. Living in the Phils, you ought to be able to get everything you need to grow macro algae as well as the macro algae.

I'd get a snorkel mask and go out looking, especially at low tide.
You can also get the marine water locally as well if you live in a decent clean water area(or can stop and get it somewhere).

If you live on the Big island(Luzon?) I know there are some aquatic plant Farmer's south of Manila about 50-100miles. Herson Moroco's family.
They raise rare Crypts.


Regards,
Tom Barr