water chemistry alk & Cal.

Hi, my water alk 8.3, Cal. 490. I think alk a little low and cal are high. I am using Bulk reef supply alk and cal supplement. I dose them same amount for both alk and cal. Can I lower the cal to keep the cal down or not. I hear people said that you much dose them same amount for them to balance so how do I lower my cal. Please help. thanks