The acid wash removed the light color scale build up on the plaster surface and has exposed the true plaster color below. The gray interior absorbs the color palate of the light spectrum instead on bouncing it away like it does from a lighter/whiter surface. For now there is much you can do with resurfacing the pool with a lighter plaster color. In the long term the plaster will naturally scale back over time and the color will gradually lighten and turn to a more blue shade.

The green look is most likely from the chemicals in the water. Most look green for awhile until the water gets properly balanced. Keep brushing and you will see the true color in about 30 days