Cara's Pool School — de powder

It's recommended to pre-mix the D.E. powder in a bucket of water prior to adding it to the filter. Once mixed, the slurry should be added slowly into the pool's skimmer while the filter is running and set in normal operation mode. The D.E. powder can also be added directly to the skimmer and without pre-mixing; but be sure to add it slowly with the pump running and ensure that all material works its way through the skimmer. As a note of safety, always ensure you do not directly inhale any powder during mixing or application.

You will need to know the internal area of your filter (square footage, usually listed on the manufacturer's label on the filter) prior to adding D.E. powder. The proper dosing amount is always listed on the powder's label; however, as an example, a 60 sq.ft. filter should take approximately 7 lbs. of D.E. after backwashing. Keep in mind that backwashing does not physically remove all of the powder and debris from the filter each time, so it's usually a good idea to only use about 80% of the recommended amount unless a full filter tear-down and cleaning has been performed.