Domakihub How to Clean a DE Pool Filter and Keep Water Crystal Clear
A step-by-step guide to backwashing and deep-cleaning diatomaceous earth filters for homes, rentals, and hotels.
Reviewed by Domakihub pool pros · 2026-06-23 · 5 min read
A diatomaceous earth (DE) filter is the gold standard for pool water clarity, capable of trapping particles as small as 1 micron — far finer than sand or cartridge alternatives. The video above walks through the full cleaning process on a typical Hayward DE filter; the steps below give you the same sequence in writing so you can follow along or work independently. Whether you manage a private villa in Crete, a rental apartment in Athens, or a small hotel pool anywhere in Greece, keeping your DE filter clean is one of the highest-leverage maintenance tasks you can do.
What Is a DE Filter and Why Does It Need Cleaning?
A DE filter uses a fine powder made from fossilised algae (diatomaceous earth) pressed onto a set of fabric-covered grids inside the filter tank. Pool water passes through those powder-coated grids, and the DE layer captures dirt, algae, and fine debris before the clean water returns to the pool. Over time the powder becomes saturated with trapped particles, pressure across the filter rises, and flow rate drops — which is the signal that cleaning is due.
Routine backwashing (reversing flow to flush the dirty DE out) handles day-to-day maintenance, but once or twice a season the grids need to be physically removed, hosed down, and inspected. In Greece's long swimming season — often running from April through October for holiday rentals and hotels — skipping this deep clean usually means visibly cloudy water and an overworked pump.
How Often Should You Clean a DE Filter in Greece?
As a general rule, backwash when the filter pressure gauge reads 8–10 psi above its clean starting pressure, or roughly every four to six weeks during the peak summer season. A full grid-cleaning (disassembly and hosing) should happen at the start of the season, at midsummer if the pool sees heavy use, and at the end of the season before winterisation. Holiday rentals with high guest turnover and pools near olive groves or sandy areas will need the shorter end of that interval.
Always note your filter's clean baseline pressure immediately after a fresh charge of DE powder — that number is your reference. A filter that reads 20 psi when clean and climbs to 30 psi is telling you it is time to act.
How to Clean a DE Pool Filter: 5 Steps
- 1
Backwash the filter first
Turn off the pump, then rotate the multiport valve to Backwash. Run the pump for 2–3 minutes until the sight glass runs clear. This flushes the bulk of the spent DE and trapped debris out through the waste line. Switch to Rinse for 30 seconds to reseat the sand bed in the valve, then switch back to Filter before proceeding. Never skip the rinse step — dirty water can be pushed back into the pool if you go straight from Backwash to Filter.
- 2
Turn off the pump and bleed the pressure
Switch the pump off completely and open the air relief valve on top of the filter tank until you hear the hissing stop and water trickles out. This de-pressurises the tank safely before you open it. Working on a pressurised filter is dangerous and always unnecessary — take the 30 seconds this step requires.
- 3
Remove and inspect the grid assembly
Unbolt or unclamp the filter tank lid (depending on your model) and carefully lift out the grid manifold. Lay the grids on a clean surface and rinse each one thoroughly with a garden hose using a straight-stream nozzle — not a pressure washer, which can tear the fabric. Look for any tears, holes, or deformed grids. A damaged grid bypasses DE powder directly into the pool and must be replaced before reassembly.
- 4
Soak for a deep clean (at least once per season)
For a proper mid-season or end-of-season clean, submerge the grids in a 10:1 water-to-muriatic acid solution for 15–20 minutes to dissolve calcium scale, or use a commercial filter cleaner overnight. Rinse thoroughly with fresh water after soaking — acid residue left on the grids will damage the fabric. Wearing chemical-resistant gloves and eye protection is mandatory for the acid step.
- 5
Reassemble and recharge with fresh DE powder
Return the clean, dry-enough grids to the tank, refit the manifold, and close the lid securely. Turn the pump on with the multiport valve set to Filter. While the pump is running, mix the correct amount of DE powder in a bucket of water (check your filter's label for the exact charge — commonly 1 lb of DE per 10 sq ft of filter area) and pour the slurry slowly into the skimmer. The powder will be drawn onto the grid fabric within about 60 seconds, restoring full filtering performance.
Rather have a pro handle it?
Get a vetted pool pro in your city — one number, booked in EN/EL/DE.
FAQ
- How much DE powder do I add after backwashing?
- After a standard backwash you only lose about a third of the DE charge, so add roughly one third of your filter's full dose. After a complete disassembly and rinse you need the full charge. Check the label on your filter tank — it will state the total powder capacity in pounds or kilograms. Adding too little leaves gaps in the grid coating; adding too much raises pressure immediately and can stress the grids.
- Can I run my pool without DE powder in the filter?
- No. Operating a DE filter without powder means uncoated grids pass all particulate straight back into the pool, and water will turn cloudy within hours. Worse, fine debris can permanently clog the grid fabric, shortening the life of an expensive component. Always recharge with the correct DE dose before restarting the pump.
- What should I do with the waste DE slurry?
- DE powder must never be discharged directly into a septic tank or soak-away, as it can clog the system. For backwash waste, direct the discharge line to a dedicated waste pit, a municipal sewer connection, or a collection point where solids can settle out. Spent DE that has been removed during a manual clean should be bagged and disposed of with general solid waste — it is non-toxic and safe to handle once dry, though you should avoid inhaling the dry powder.