There are also other marine and brackish plants to consider:
https://www.floridamuseum.ufl.edu/southflorida/habitats/seagrasses/species/
http://www.reefland.com/2012/07/19/...rue-flowering-plants-in-your-marine-aquarium/
Your best bet might be shoal grass, which seems to tolerate a wide range of salinities, and appears to do well in salinities as low as 10ppt (SG 1.0075). I have seen vast beds of shoal grass in the estuaries around Pensacola and Destin, FL.
This article below indicates that shoal grass will be OK in salinities as low as 9ppt (SG 1.0068) It will die when salinities go down to 3.5 ppt (SG 1.0026)
http://www.jstor.org/stable/3798928?seq=1#page_scan_tab_contents
I know that there are a number of online retailers that will sell some of these grasses, but I don't know if they would ship to Belgium.
https://www.floridamuseum.ufl.edu/southflorida/habitats/seagrasses/species/
http://www.reefland.com/2012/07/19/...rue-flowering-plants-in-your-marine-aquarium/
Your best bet might be shoal grass, which seems to tolerate a wide range of salinities, and appears to do well in salinities as low as 10ppt (SG 1.0075). I have seen vast beds of shoal grass in the estuaries around Pensacola and Destin, FL.
This article below indicates that shoal grass will be OK in salinities as low as 9ppt (SG 1.0068) It will die when salinities go down to 3.5 ppt (SG 1.0026)
http://www.jstor.org/stable/3798928?seq=1#page_scan_tab_contents
I know that there are a number of online retailers that will sell some of these grasses, but I don't know if they would ship to Belgium.