i know where you got the one big one from. last time i checked he wasnt a big secret. just likes to "get outta discus" and liquidate his spares every couple months. Turks are the most common and one of the hardiest strains.
how big was the turk when you got it 3 months ago? healthy discus with good conditions will put on an inch every month, and i dont think you got it as a pea sized fry
"crustations"
in your sponges mean your either overfeeding, not cleaning nearly enough, or both