devices , apparatus , systems , and methods for retrofitting or providing new water treatment vaults and chambers , with a floatable skimmer on tracks above a solid shelf that constricts and restricts water during low and medium flows for maximum detention time to allow for greater storm water treatment , and for high flows allows for the skimmer to automatically adjust to allow for greater conveyance of storm water flow . the skimmer can have float across an upper edge with side edges having both centering and load bearing wheels that slide up and down within tracks that are mounted to side walls of storm water treatment chambers and vaults . additional embodiments include multi - chamber vaults and chambers with baffles separating sediment chambers . additionally screen treatment systems can be used with the chambers and vaults . additionally , the skimmer panels can be positioned so that lower edges can sit on top of outer edges of the shelfs , or form a gap between the top of the outer edge of the shelf and the lower edge of the moveable panel , or have a gap between a hanging down skimmer panel and a front edge of the shelf .