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.
A: CYA, or cyanuric acid, is a stabilizer or conditioner that is used to reduce the rate of composition of free available chlorine in pools that are exposed to the sun's ultraviolet rays. Dissolving CYA into a swimming pool helps to make free chlorine last significantly longer.