A flotation tank for removing a contaminant from fluid input into the flotation tank, the flotation tank comprising: a floor defining a bottom of the tank and a depending wall defining the sides of the tank; a series of adjacent chambers within the tank separated from each other by dividing walls, each chamber comprising a sloped weir for inducing a rotational current within the chamber, the sloped weir bisecting each of the chambers; a skim oil trough spanning each chamber and separated from each chamber by a skimming weir, the skimming weir opposite the sloped weir; an inlet in fluid communication with a chamber of the series of adjacent chambers for inputting a fluid comprising a contaminant, the inlet positioned towards an upper region of the depending wall and situated proximate the sloped weir of the series of adjacent chambers for inducing a rotational current to fluid input into the chamber; each chamber in fluid communication with the adjacent chambers via an interconnecting passage positioned substantially towards the bottom of the dividing wall of each chamber and substantially opposite the skim oil trough, the interconnecting passage for allowing passage of fluid from a chamber to a backside of the sloped weir of the adjacent chamber; a connector port in the dividing wall between two adjacent chambers for providing fluid communication between the two adjacent chambers; a fluid passage (70, 85) in the sloped weir of at least one of the chambers of the series of adjacent chambers allowing for fluid transfer between adjacent chambers through the sloped weir of the at least one chamber; and an outlet in fluid communication with one of the chambers of the series of adjacent chambers outputting produced water; wherein the connector port and the fluid passage (70, 85) are situated in alternating adjacent chambers; wherein the interconnecting passage is positioned at one end proximate the base of the sloped weir and at the other end in proximity to a backside of the sloped weir of the adjacent chamber; wherein the connector port is positioned in the base of the dividing wall proximate the skimming weir; and wherein each set of adjacent chambers comprises either a connector port or a fluid passage (70, 85) in alternating format allowing for equalization of the fluid level in adjacent chambers while preventing short circuiting of the fluid through the tank to the final chamber. a floor defining a bottom of the tank and a depending wall defining the sides of the tank; a series of adjacent chambers within the tank separated from each other by dividing walls, each chamber comprising a sloped weir for inducing a rotational current within the chamber, the sloped weir bisecting each of the chambers; a skim oil trough spanning each chamber and separated from each chamber by a skimming weir, the skimming weir opposite the sloped weir; an inlet in fluid communication with a chamber of the series of adjacent chambers for inputting a fluid comprising a contaminant, the inlet positioned towards an upper region of the depending wall and situated proximate the sloped weir of the series of adjacent chambers for inducing a rotational current to fluid input into the chamber; each chamber in fluid communication with the adjacent chambers via an interconnecting passage positioned substantially towards the bottom of the dividing wall of each chamber and substantially opposite the skim oil trough, the interconnecting passage for allowing passage of fluid from a chamber to a backside of the sloped weir of the adjacent chamber; a connector port in the dividing wall between two adjacent chambers for providing fluid communication between the two adjacent chambers; a fluid passage (70, 85) in the sloped weir of at least one of the chambers of the series of adjacent chambers allowing for fluid transfer between adjacent chambers through the sloped weir of the at least one chamber; and an outlet in fluid communication with one of the chambers of the series of adjacent chambers outputting produced water; wherein the connector port and the fluid passage (70, 85) are situated in alternating adjacent chambers; wherein the interconnecting passage is positioned at one end proximate the base of the sloped weir and at the other end in proximity to a backside of the sloped weir of the adjacent chamber; wherein the connector port is positioned in the base of the dividing wall proximate the skimming weir; and wherein each set of adjacent chambers comprises either a connector port or a fluid passage (70, 85) in alternating format allowing for equalization of the fluid level in adjacent chambers while preventing short circuiting of the fluid through the tank to the final chamber.