IME, I had a funny reaction with mine. I was keeping my phosphates below .13ppm and mine never fully expanded like have seen others. Well moving forward 5 months later, had to have knee surgery and was down for about a month. So my tank was neglected during that time. During this time my phosphates climbed to about 2.5 ppm, nirates got to about 30ppm and guess what...my hammer was open to the fullness. It was so beautiful and I noticed my Duncan also expanded out more. So I guess every tank is different. IME, my LPS likes the dirty water