Any tips on brightening up my BTA?

[gaki]

Hello. I've had this BTA for about 6 months now and it started out like picture 1, but over time (pictures 2,3), it has turned into picture 4 (taken today). I feed it NLS or PE mysis pellets every few days and keep it under AI prime HD LEDs and it is bubbly but not very colorful. Any tips on helping it color back up? Also I'm pretty sure it has shrunk a bit.

 

[Jekyl]

Full tank shot, parameters and lighting intensity and schedule?