Acrylic spa. Water has a greenish tint to it. pH is at 7.4, Br around 2. The last time I filled up the spa I did NOT use a metal sequestrant. Is that my culprit? I'm in phoenix and we have "hard water" with calcium always being a problem. If that is the problem, am I able to add that even now to my month old water? Normally instructions are to add while filling up but I'm assuming I can add any time.