Systems, methods, and apparatuses of the present disclosure generally relate to dissolvable plugs for separating fluids in a wellbore. A dissolvable plug includes a first end comprising a first fluid barrier. The first fluid barrier includes a polymer film. The dissolvable plug also includes a second end opposite to the first end. The second end comprises a second fluid barrier. The second fluid barrier comprises a polymer film. The dissolvable plug includes a solid structure made of a sand and salt mixture.