OK, I have a 30 gallon tank that is about 2.5 months old. My ammonia is 0, my nitrites are 0, Nitrates are 20 ppm, PH 7.8 .... I bought a cleaner shrimp and a peppermint shrimp 8 days ago. Yesterday afternoon I bought a new piece of live rock (9 lbs) from my local saltwater store cuz I...