Hi, when my pool was built 3 years ago, I made the mistake of hiring a general contractor who didn't know what they were doing. They built a water feature with natural rock and immediately upon filling the pool after my interior was set, it stained under the rocks. After my pool was started, I hired a waterfall company to fix the actual water feature. What was it exactly that stained the pool from the rocks? Are rocks suppose to be prepared a certain way before putting water in the pool? I am trying to learn if acid washing is my only option for the staining.