If your chlorine is running high, or you are doing a shock treatment, it's important to be aware of the affect it may have on other water quality parameters such as pH.
Sanitizer type / pH / affect on pH
Sodium hypochlorite / 9-14 / Raises
Calcium hypochlorite / 8.5-11 / Raises
Trichlor (UV stable) / 2.8-3.5 / Lowers
Dichlor (UV stable) / 6.5-6.8 / Neutral
Bromine / 4.8 / Lowers
Allowed pH range: 7.2-8.0
Recommended pH range: 7.4-7.6