I started cycling my 80 gallon reef 9 days ago. I used crushed coral substrate that had been previously used in another well maintained tank, and it had been sitting covered in a bucket for a few months. I added live rock almost immediately, and started the cycle with some brine shrimp on day 1, and then after about 5 days I added a small Damsel and a couple Chromis. I tested my water after day 6 with a small spike of ammonia .50. Since then the ammonia has leveled off to 0. I never saw a spike in nitrites as it stayed constantly at 0, and now I'm seeing a spike in nitrates somewhere between 10ppm and 20ppm. I know the cycling period is supposed to take somewhere between 4-6 weeks, but these water parameters are strange. Could it be that because I used substrate from an established tank that is cycled faster? Or am I miss reading something all together.