Generally, cylinder shaped tanks are used to store liquid. However, some specially designed containers are also presented. In this research 2, 3, 4, 5 cylinders are continuously integrated into one vessel to make special storage tanks. The laboratory equipment was a copy of a tank which is used for industrial application. In this work, the effect of the shape of the container was investigated on mixing. Stirring was achieved by an external pump. The residence time was 3 h as in the industrial case. The aim was to examine the influence of special shape on mixing efficiency by using constant residence time. By utilizing lower residence time, the mixing efficiency might be risen however with the lower residence time the flow rate should be increasing consequently the energy consumption of recirculation become greater. Consequently in all experiments the residence time, calculated by the volume and flow rate, was constant. Borax solutions were used as a stratified liquid layer. The density of the upper layer was 1.0022 g/cm3 and the lower layer was 1.0136 g/cm3 density. The inlet was positioned above the liquid level. Concentration changes have been followed by electrical conductivity measurements. Residence time distribution and recirculation measurements were achieved. The data was evaluated by the time request to reach 95 % homogeneity. The concentration differences among the sampling points in time also were examined. The results were compared with the examination with a conventional cylinder tank. The experiments indicate that free convection is more dominant than forced convection. The results show reproducibility. The effect of the shape of the tank on mixing by recirculation is remarkable.