Will my discus fish grow with multiple water changes?

I have a 180 gallon long tank.i am great with aquariums but even gurus need help.i have always kept amazing looking fishtanks but my other aquarist buddies although they seek my help for water quality and disease removal have always had fish that outgrow mine.i never lose fish and always maintain good water.but my fish always take to long to grow.some better than me who at times school me said i need to do more water changes.i only see her rarely because she is to far and i dont call because with he accent she is hard to understand.i change 33 percent a week.please help.thanks.