[Clownfish518]

I do 25% water changes weekly myself, but one of my friends does 50-75% water changes regularly. I don't know many people who know as much about marine aquariums as he - he has been published in Advanced Aquarist for example. Keeps everything from ritteris to sharks.

I don't follow his regimen, but he has taught me that large water changes are nothing to be intimidated by. As long as the temp, pH, alk, and salinity match it should be okay.