I've kept the FC reading between 15 and 20 (closer to 20) for the past seven days. However, overnight my FC readings have dropped the following: Sun -5.5, Mon -5.5, Tue -5.5, Wed -5.5, Thu -5.5, Fri -8.5, Sat -3.5. I have also checked pH daily and it wants to drift up to 8.2 or higher. I've...