The ankh is an ancient Egyptian symbol. It looks rather like a key. The ankh symbol was used in hieroglyphics and in designs. One of the artifacts carefully placed in King Tut's tomb was an ankh. The ankh must have meant something important to the ancient Egyptians, but we're not sure quite what that was.
You may want to look at my article HERE on lowering stabilizer. Basically if you use chlorine tablets, they have stabilizer in them and over time, can over stabilize the pool water and will need to be diluted. Also calcium levels that are high, rainfall can be a benefit to diluting the water as well.
Some chlorine enhancers contain sodium bromide, and some formulations are ammonia based. The addition of ammonia and lots of chlorine creates monochloramines, which act well on many types of algae. Sodium Bromide creates bromamines in the pool, at least temporarily.