Diatomaceous Earth (DE) in Pools

This guide explains how diatomaceous earth (DE) is used in pool filtration. It’s designed for Flow technicians and homeowners to understand what DE does, how to use it, and how to handle it safely.

What It Is

• Material Name: Diatomaceous Earth (DE)
• Form: Fine white powder made from fossilized diatoms (microscopic algae)
• Primary Use: Coats DE filter grids to trap extremely fine particles — down to 2–5 microns
• Not a chemical sanitizer: DE is a mechanical filter aid, not a disinfectant

Why Use DE?

• Provides the finest level of filtration available in residential pool systems
• Helps remove fine debris, dust, pollen, algae, and some bacteria
• Improves water clarity and overall filter performance

How to Add DE to a Pool Filter

1. Backwash or clean the DE filter to remove used media
2. Make a slurry (mix DE powder in a bucket of pool water)
3. With the pump running, slowly pour slurry into the skimmer
4. Do not add dry DE powder directly — always pre-mix
5. Use manufacturer guidelines to measure the correct amount (usually 1 lb per 10 sq ft of filter area)

How Much DE to Add

• General Rule: 1 lb of DE powder per 10 square feet of filter surface area
• For example:
  • A 48 sq ft filter needs ~4.8 lbs of DE
  • A 60 sq ft filter needs ~6.0 lbs of DE
• After Backwashing: Add 90% of the full DE capacity (e.g. 5.4 lbs for a 60 sq ft filter)
• After Full Cleaning (opening and hosing off grids): Add 100% of the DE amount (e.g. full 6.0 lbs for a 60 sq ft filter)
• Use a 1-lb DE scoop (often included with DE bags) for accurate measuring

How Often to Add DE

• Every time you backwash or clean the filter — DE MUST BE REPLENISHED
• Check pressure gauge — if pressure rises 8–10 psi above clean level, it's time to backwash

Safety & Handling

• Do not inhale DE dust — it can cause respiratory irritation or lung issues with long-term exposure
• Wear a mask and goggles when handling dry DE powder
• Rinse any skin or eye contact with water
• Store in a dry, sealed container away from wind and moisture
• Do not dispose of DE into storm drains — dispose of used DE in accordance with local regulations

FAQs

• Can I swim after adding DE? Yes — DE is added through the filter system, not directly into the pool
• What happens if I add too much DE? It can clog the filter and reduce flow — always measure carefully
• Can I use DE in a cartridge or sand filter? No — DE is only compatible with DE filters

Need Help?

Flow’s technicians are trained to handle DE filtration systems properly and safely. Contact our team for support with filter cleaning, DE dosing, or system troubleshooting.