I would not expect them to drop significantly from coral uptake. You can get it out of the rock by removing it from the water repeatedly. Every time you remove some from the water, more leaches out of the rock into the water for you to remove. Repeat this cycle enough times and the level in the tank will eventually decrease and stabilize at a lower value. GFO works well for this. It may take several weeks to reach your goal, but it is working even if you don’t notice a huge impact right away. Just have to be patient and continue pulling the phosphate out of the water.Well the reason is 100% in the rock because I have crushed coral as my substrate, I do water changes rather to control nitrates level, and yet still phosphates. So about them, I think that with the growth of corals and algae as the tank matures, they should go away because after all, it cannot be that there's an infinite amount of it in my rock