Chara loves limey soils. Don't dismiss the productivity of chara ponds. Without fertilization they can be remarkably productive ponds particularly when combined with right kinds of forages. Chara is a host to the periphyton community and one member is a blue-green algae with which it is symbiotic. This algae fixes nitrogen and naturally fertilizes the Chara. Rice paddies do not lose their productivity, even over centuries of production, largely because of of chara species and their symbiotic blue-green algae. In addition to fertilizing chara, the algae fertilize the pond when recycled by organisms. An example of such organisms are PK shrimp which thrive in ponds with chara and with no additional fertilization. Chara tends to make water clearer, truth be told, it is the organisms living on the chara that do the bulk of that lifting.

Water clarity isn't always an indicator of poor fertility. You may have community of organisms that very efficiently graze and consume phytoplankton keeping the clarity high. We are learning that production in highly grazed systems are not adversely affected by the grazing. Under these conditions all organisms thrive.