Yep, I'm not doing that! I'm in the process of tearing it all out. The stuff is not porous so no beneficial bacteria can ever take hold. I think i finally beat it, but I'm not gonna take a chance on having to nuke my tank after all my corals are grown out.My Carib sea soaked phosphates and then would leach them back out causing algae issues. Dealt with this for 5 years before it went away.