Wanted to know if there was a "standard" height to place my fixture. I'm gonna be changing my lighting over to a 400W Radium. In a Sunlight Supply Lumen Max Elite fixture, with a Blue Wave Hqi ballast. Since I don't have a par meter I have no idea where I should place it to get the best results. My tank is 20" tall x24"wide x24" deep. I have an enclosed hood now but can take it off to accomadate the placement of this new fixture. So If anyone either has a par meter they wanna play with or knows of height estimate please let me know.(scratch)