Chlorine

(FC) Free Chlorine

(FC) Free chlorine shows the level of disinfecting chlorine available to keep your pool sanitary.
The level of FC you need to maintain depends on your CYA level and how much your pool is used.
It is important not to allow the FC to get too low, or you run the risk of getting algae and/or having an unsafe pool.
FC is raised with bleach, liquid chlorine, liquid shock, trichlor tablets/pucks/sticks, dichlor powder, cal-hypo powder/capsules, or lithium hypochlorite.

Combined chlorine is an intermediate breakdown product that is created in the process of sanitizing the pool.
Chloramines are formed as a product of combining chlorine with body oil, sweat, urine, saliva, lotions, and feces.
Chloramines (CC) are poor sanitizers and have a gaseous tendency.
CC indicates that there is something in the water that the FC is in the process of breaking down.
If CC is above 0.5 your FC will be brought to shock levels according to your CYA levels until CC reaches zero.