Thanks for your comment, Diana.
A long, slow acclimation is, to my understanding, even more important for plants than fish.
I have tried several plants in brackish before as well, with lousy success.
Out of the 10 red mangrove pods I got only four are alive in a 250 gal brackish tank (after 2 years) . But I know I have srewed it up myself by not letting them settle in one place from the beginning. At least the word is that they do not tolerate moving their roots.
At first I tried to keep the mangroves with their roots freely in water.
The roots an sich are not that sightly when they grow:

They never reached the 2' water depht to the bottom.
Later I made an elevated "pot" for them, loaded it with plant growing subtrate and they partly settled. Not too much growth, still.
And they are under 150w HQI's.
I might still try and find a way to fit some of them in this tank, propably letting them grow out of the top to receive natural sunlight. I don't know if they will grow in dryish room air, though.
Anyone with any thoughts on plants in brackish, please do chime in!
Meanwhile, I got the new glass.
Here's the tank now, frames, rear glass and stand painted semi-matt black. Left end glass cut to fit a bit of ventilation to fiddle with the potential front glass condensation:
