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.
How to Add Chlorine to a Pool When chlorine is placed in water, it has a sanitizing effect and is therefore used in pools where water is not drained... How to Raise Stabilizer in Swimming Pools Cyanuric acid stabilizer will help you to save considerable time and expense in maintaining the chlorine level in your pool.