Notice that there is a variation in the water color, even though the plaster color is the same in each individual category. This is due to a multitude of factors including but not limited to the reflections of the surroundings of the pool, the sky at that moment, house color, landscaping, etc. combined with the color of the plaster. The color is also different in the same pool according to the varying depths of the water. In short, you can have the same plaster color as your neighbor a block away, and the water color can be slightly different. This is a normal characteristic of pool plaster. 

White Plaster

Pacific Blue Plaster

Tahoe Blue Plaster

Sea Foam Green Plaster