The first step when determining your grid size is to check your owner’s manual to find the make and model listed in its contents.
Now that your water is no longer circulating through your filter system, switch your valve to the "Closed" position. When changing your valve setting be sure to always turn the lever in the same direction. By using clockwise and counter clockwise turns of the lever you may cause unseating of the valve key gasket. This unseating may cause leakage from your waste port.
A way of releasing the tanks grip is by tamping it with a rubber mallet preferably or very gently with a regular hammer. Be careful not to strike filter too hard as you may damage the shell. After tamping the entire circumference once or twice you should be able to lift the top half off by using the handles of the filter.
If no tag is present then you will have to remove the grid assembly from the tank to measure the lengths and widths of a grid
On top of the grid assembly there will be a spacer tube you must remove to get to the locking bolt of the manifold assembly, Remove my pulling up and place to the side.
The D.E. filter grid assembly is now removed from the filter. We can begin measuring the grids. For most of the popular brings like Hayward or Pentair, the measurement you will most need D.E. grid length. The standard lengths are, 12", 18", 24", 30" and 36". Our grid measures as 30" inches long.
Using the handles we used to remove the assembly place the filter grid assembly into the filter body. When placing the grid assembly, align the manifold pipe inlet and manifold pipe. As the grids are lowered into the body, be sure to align the manifold inlet with the filter inlet pipe. These must be connected for water to flow correctly through your filter system.
Place the small tube spacer on top of the manifold covering the lock nut.