A method for treating large water bodies for recreational uses, including artificial excavated or floating structures with bottoms comprising flexible membranes, wherein the water body has a surface area of at least 7,000 m 2, wherein the method comprises: (a) Applying an effective amount of a flocculant to water in the water body to maintain turbidity of the water below 2 NTU, wherein the flocculant flocculates suspended solids in the water into particles that settle to the bottom of the water body. (b) operating a mobile suctioning device to maintain an increase in the black component of the bottom's color below 30% based on the CMYK scale, wherein the mobile suction device moves on the bottom of the water body and suctions a portion of water from the bottom of the water body containing settled particles, wherein the device is capable of moving and cleaning at a rate of 10,000 m 2 per 24 hours, and wherein operating the mobile suctioning device does not re-suspend more than 30% of the settled particles in the area on the bottom of the water body cleaned by the mobile suction device; (c) operating a filtration system for filtering the water suctioned by the mobile suction device and returning the filtered water to the water body, wherein the water suctioned by the mobile suction device does not exceed 10% of the total water volume of the water body in a 24 hour interval; (d) operating a degreasing system to maintain a surface water layer having less than about 20 mg/L of floating greases within a top-most 1 cm of the surface water layer, wherein greases from the surface water layer flow into the degreasing system are removed, wherein the degreasing system comprises a skimmer system and an overflow apparatus in combination with a screen, a coarse filter, or a filter, and wherein the water that has passed through the degreasing system is returned to the water body; and wherein a control system activates the application of flocculants, the filtration of the water suctioned by the mobile suctioning device, and the operation of the degreasing system. (a) Applying an effective amount of a flocculant to water in the water body to maintain turbidity of the water below 2 NTU, wherein the flocculant flocculates suspended solids in the water into particles that settle to the bottom of the water body. (b) operating a mobile suctioning device to maintain an increase in the black component of the bottom's color below 30% based on the CMYK scale, wherein the mobile suction device moves on the bottom of the water body and suctions a portion of water from the bottom of the water body containing settled particles, wherein the device is capable of moving and cleaning at a rate of 10,000 m 2 per 24 hours, and wherein operating the mobile suctioning device does not re-suspend more than 30% of the settled particles in the area on the bottom of the water body cleaned by the mobile suction device; (c) operating a filtration system for filtering the water suctioned by the mobile suction device and returning the filtered water to the water body, wherein the water suctioned by the mobile suction device does not exceed 10% of the total water volume of the water body in a 24 hour interval; (d) operating a degreasing system to maintain a surface water layer having less than about 20 mg/L of floating greases within a top-most 1 cm of the surface water layer, wherein greases from the surface water layer flow into the degreasing system are removed, wherein the degreasing system comprises a skimmer system and an overflow apparatus in combination with a screen, a coarse filter, or a filter, and wherein the water that has passed through the degreasing system is returned to the water body; and