rift lake plants

I'm at home, not at the office, so I don't have access to all my
data and I'm going on memory. If you want more specific details
and accurate numbers ask me again after Jan. 8. I don't have such a
tank as  yours but I am an aquatic botanist and have done lots of field  
work in BC. The cariboo plateau lakes often have no exit and are in a
region of higher evaporation than rainfall for much of the year so
they accumulate salts. They tend to be magnesium sulphate lakes
rather than calcium carbonate systems. Once pH's get up over 10.0
hardness gets over 1000 and conductivity exceeds 10,000 the species
list gets quite short. What does remain is Zannichellia palustris, 
Myriophyllum sibiricum (exalbescens), Ruppia maritimum, Scirpus 
lacustris (sensu lato) and Typha latifolia. The latter two are of course too 
large for an aquarium.