Copy this code into your page. Free to use with the credit link.
advertisement
The DE charge math
fresh charge = filter sq ft ÷ 10 lbs · after backwash = × 80% 1 scoop ≈ ½ lb · 6 cups ≈ 1 lb
DE filters clean by coating fabric grids in a layer of diatomaceous earth — the powder IS the filter; the grids just hold it. Backwashing flushes most but not all of the old cake, hence the 80% rule: a full recharge on top of residue over-packs the tank.
A worked example
A 36 sq ft filter after backwash: 3.6 × 0.8 ≈ 2.9 lbs — six scoops, slurried into the skimmer while the pump runs. After the annual teardown and hose-down of the grids, it gets the full 3.6 lbs. Write your number on the cheat sheet; it never changes unless the filter does.
DE, sand, or cartridge?
DE filters polish finest (down to ~3 microns — genuinely sparkling water) at the cost of the most maintenance ritual. Sand is the set-and-forget workhorse (media calculator); cartridges split the difference. If you own DE, you chose sparkle — this page just makes the ritual exact.
Frequently asked questions
How much DE do I add to my filter?
Fresh charge (new grids or after a full clean): 1 lb of DE per 10 sq ft of filter area — a 36 sq ft filter takes 3.6 lbs. After a routine backwash: about 80% of that, since some old cake remains.
How many scoops of DE is a pound?
The standard DE scoop holds about half a pound, so it's 2 scoops per pound. No scoop? Roughly 6 cups make a pound. A 48 sq ft filter's fresh charge is 4.8 lbs — about 10 scoops or 29 cups.
How do I add DE powder?
Pump running, make a slurry: mix the DE with water in a bucket and pour it slowly into the skimmer. It travels to the filter and coats the grids in minutes. Never add DE to a filter that isn't running — it needs flow to coat evenly.
What happens with too much or too little DE?
Too little exposes the bare grids to debris (shortens their life and lets fines through); too much cakes into bridges between grids and spikes pressure. The square-footage math exists because both directions cost you — measure, don't scoop by vibe.