If I remember correctly, the other member said your GSP is 1.5inch, so freshwater is ok for now. It will take approximately another 1 - 1.5 years for it to convert from freshwater to brackish and then finally marine. If you want, you could keep some java moss, marimo balls, and java ferns with the GSP during low salinity levels. Then once it needs higher level brackish water, then you won't be able to keep plants. It probably won't tear up the plants, but you will only be able to keep plants with it maybe 1 more year until it needs high brackish water.