Morning everyone ...I am thinking I would like to make use of a wave or surge maker when I overhaul my tank in the new year. I question I have is ... How much free play in glass height should I have above the "calm seas" water line to avoid water coming over the ends of the tank when the water gets moving? If large enough power heads are used do theses devices create noticeable surface action that even requires addition glass height? I have NO experience with them and have never seen one in use. Any help for those with first hand experience would be welcome