I have bought a 20 lb. piece of nice coral from our local store. It is dry--and they said I should treat the rock with bleach and water. then let it dry for a week to let the bleach dissipate -- after washing rock thoroughly with fresh water. My question is ---- How much bleach or Clorox or thr Ratio of bleach to water ??? Maybe 1 part bleach and 2 parts water??? or does it matter??/ Thanks !!!! P.S. the is dry but has green algae color on it .