I scraped mine of with an Xacto knife, then rinsed each rock in outgoing changewater. The valonia just got worse. As a last resort, I boiled each rock (about 40 lbs), then cured it. Once cured, all the rock went into a different tank as base rock. After 4 months, the boiled rock is beginning to get coralline on it.
As for the heaters and powerheads, I soaked them in vinegar. The tank was scrubbed down with tapwater. I felt awful killing all that rock, but I felt I had no alternative as I had battled valonia for going on a year and it only got worse each time I carefully scraped it off. Plus, the emerald crab I bought ate all the OTHER algae and some of one of my lps corals and didn't touch the valonia
