[monster mac]

Usually plants grow taller or reach for the top if they aren't recieving the amount of light they require. So they grow thin and tall to get closer to the light. Since he is obviously happy now with the amount of light he will fill in alot and stay short.(naturally tall will still grow naturally)

 

[monster mac]

or grow it out in a low tech tank and then move it to your high tech tank to then fill out...i wouldn't lower you current tanks lighting especially if you're trying to grow some highlight plants (ground cover)