I have 9 discus in my 90 gallon tank. Filtered by a fx4 and a fx5. Temp 87. Ph7.6, no ammonia, no nitrites, nitrates 10ppm. I have 1/4 inch of gravel in the tank. I change 50% water 2 times a week. I Do not age water. Have had these discus for over 7 months. Size range from 5 to 51/2 inches. Would really like some to pair up. But it not happening. Is there something I can do to stimulate them breeding. A friend suggested play some Barry White music. Lol.