Questions on growing red mangrove

[itelshot]

A week ago I managed to buy 3 red mangrove sprouts, I put them in water I collected from a country river and boiled then. The plan is to wait until they grow a few levels of leaves month-2 and at the same time gradually add salinity from the tank. I have now put them grow under a 36 watt LED phyto strip.
As I know it's better to plant mangroves in a shallow aquarium, but have what have. How should I gradually lengthen it to submerge it more?
The plan is to then put 2 somewhere near the overflow, and one on the right.

As far as I've heard, you can submerge it under water and with enough light the leaves will fall off and it will break through and grow on its own towards the surface and the air

 

[Mr. Mojo Rising]

As far as I've heard, you can submerge it under water and with enough light the leaves will fall off and it will break through and grow on its own towards the surface and the air

Thats exactly what happened to mine, I have mine in 18" depth tank, all leaves fell off and it actually quickly grew past the water line and grew leaves. But I started it off in a very dirty tank, which I think helped it. Once I was sure the the tree was growing and doing well, I moved it over to my seahorse tank.