How can I change the sand in my haywood sand filter?

Question:

Answers:
Turn off the pump.
Take the top off the filter being careful not to pull the center pipe out.
Use a shop vac to suck out the sand but don't push hard on the sand bed.
About 1/2 way down go slowly as you will find "laterals" buried in the sand bed.
Once you get to the laterals suck the sand out from between them and brush the sand off them.
You don't have to get all the sand out but don't leave chunks either.

To fill it
Add enough water to cover the laterals inside by two inches of water.
Pour the sand in slowly so that it settles around the laterals instead of pushing down on them.
Once the sand is covering the laterals you can pour the rest of it in less carefully.
Brush off the sand from the connections and wash them with water.
Replace the top, turn the valve to backwash, turn on the pump, open the bleeder valve to let air escape, backwash/rinse as normal and you're done.

You may have a little residual sand being expelled back into the pool but this is normal and will stop. If it continues then you may have cracked one of the laterals inside the sand bed.