Covertech Grando automatic rigid slatted free form pool Covertech – Grando pool cover  This 30 x 90 feet pool is an absolute Free Form Pool Cover and it stops the evaporation by 80% on this 190.000 gallon vessel. . On this project we hide the pool cover in the floor of the pool. Remember NO TRACK, ANY SIZE OR SHAPE OF POOL, NO PUMPING RAINWATER OFF, 80% Energy Efficient . nothing MORE nothing LESS