30 With the filler hole taped up, the tank was rotated slowly in all directions to completely coat all surfaces. The tape was then removed, the tank left to stand for 10 minutes, and then the process repeated so the excess sealer could re-coat the surfaces. This tank is so small (around 6 gallons) that I only used one of the two sealer bottles. When the tank was standing between "rotating sessions" I opted to let it stand on each end, as these were the most corroded areas. However, it's important not to let the sealer drain to one area in a thick puddle and dry.