Diatomaceous earth filters are the most powerful filtration option in the residential pool market — but only when properly charged. Too little DE and water bypasses the grids unfiltered. Too much and you get premature pressure rise and restricted flow. This guide covers exact amounts by filter model, when to recharge versus deep-clean, and how to add DE cleanly.
The universal starting point for DE dosing is 1 lb of DE powder per 10 sq ft of filter surface area. After a standard backwash, you add back roughly 80% of the full charge (since backwashing is never 100% efficient — some DE always remains on the grids).
Record each pool's exact DE filter model in PoolLens. Pull up the notes on arrival and you know the exact charge without looking anything up. One less thing to carry in your head across 20+ accounts.
| Filter Model | Filter Area (sq ft) | Full Charge | After Backwash |
|---|---|---|---|
| Hayward Pro-Grid 24 | 24 | 2.4 lbs | ~2 lbs |
| Hayward Pro-Grid 36 | 36 | 3.6 lbs | ~3 lbs |
| Hayward Pro-Grid 48 | 48 | 4.8 lbs | ~4 lbs |
| Hayward Pro-Grid 60 | 60 | 6.0 lbs | ~5 lbs |
| Pentair FNS Plus 36 | 36 | 3.6 lbs | ~3 lbs |
| Pentair FNS Plus 48 | 48 | 4.8 lbs | ~4 lbs |
| Pentair FNS Plus 60 | 60 | 6.0 lbs | ~5 lbs |
| Jandy DEV 48 | 48 | 4.8 lbs | ~4 lbs |
| Jandy DEV 60 | 60 | 6.0 lbs | ~5 lbs |
Always verify the label on the filter tank — it lists the rated surface area and manufacturer charge recommendation, which takes precedence over any generic guide.
Every time you backwash, you must add DE back. Backwashing removes 20–30% of the DE along with the debris. Without recharging, the grids are partially exposed and water passes through unfiltered — you'll see it in the water clarity.
Once per season (or when pressure rises and backwashing no longer brings it down), the filter requires full disassembly and manual grid cleaning. Remove the manifold, pull each grid, and hose them off carefully. Inspect grids for tears, collapsed spines, or calcification. Replace any damaged grids — a single torn grid means unfiltered water returning to the pool.
DE that has been in service through a heavy algae bloom or multiple chemical treatments can develop calcified deposits that hosing won't remove. Soak grids in a 10:1 water-to-muriatic acid solution for 15 minutes, then rinse thoroughly before reinstalling.
Never dump dry DE powder directly into the skimmer. It puffs up and can partially escape the skimmer basket, causing a brief cloudy return. Always make a slurry first.
Used DE can typically be disposed of in regular trash (check local codes). Do not dump backwash water containing DE into storm drains — in many states this is a code violation. Route backwash to a sanitary sewer clean-out or a dedicated drainage area on the property. Never allow DE-laden backwash to reach waterways.
If DE disposal is restricted in your service area, perlite-based alternatives like Celite 545 or commercial "DE Alternative" products provide similar filtration performance and are generally accepted for standard drain disposal.
Store filter model, surface area, and charge amount for every DE pool in your route on PoolLens. Pull it up in seconds, offline, from anywhere on the job site.
Open PoolLens Free →After a standard backwash, add back about 80% of the original full charge — roughly 1 lb of DE per 10 sq ft of filter area. Full amounts depend on your specific filter model.
Yes. Over-charging causes the DE to cake and restrict flow, raising pressure prematurely. Never exceed the manufacturer's recommended charge by more than 10%.
Food-grade or pool-grade DE is safe when wet, but the dry powder is a nuisance dust. Wear an N95 mask when handling dry DE to avoid inhaling the fine silica particles.
Perlite (sold as Celite or DE Alternative) is a safer substitute with similar filtration performance. It lacks the crystalline silica found in mined DE and is easier to dispose of in many jurisdictions.