Cartridges: rinse, then soak
A hose rinse removes what you can see. It does not remove the oils, sunscreen and scale that clog the fabric at a level you cannot — which is why a rinsed cartridge often shows no pressure improvement at all. The rinse is maintenance; the soak is the actual clean.
- Hose the pleats out top to bottom, fanning the spray between them rather than blasting the fabric.
- Soak overnight in a cartridge degreaser to lift oils and lotion.
- Rinse thoroughly. Only then, if the pool is in a hard-water area, soak briefly in a dilute acid solution to strip scale.
- Rinse again, let it dry completely, and refit.
Degrease before acid, never after
Acid on an oily cartridge sets the oils into the fabric permanently. Do it in that order and a cartridge lasts years; do it backwards once and you have bought a new one.
DE grids: strip and inspect
Once a year, take the whole assembly out rather than just backwashing it. Hose every grid, look along each seam for tears, and check the manifold for cracks. A single split grid dumps DE back into the pool and shows up as a fine grey dust on the floor that no amount of vacuuming permanently fixes.
Reassemble in the right order, recharge to the label weight, and note the clean pressure on the tank.
Sand: when the bed is finished
Sand does not wear out from use so much as from chemistry: grains round off, oils bind them into clumps, and the water carves channels straight through the bed. A channelled filter shows normal pressure and filters nothing, which is the most misleading failure on the whole equipment pad.
| Symptom | Likely cause | Action |
|---|---|---|
| Pressure normal, water dull | Channelled or clumped bed | Change the sand |
| Pressure high days after backwash | Oils binding the top layer | Deep clean, then change if it returns |
| Sand in the pool | Cracked lateral or standpipe | Strip the tank, replace the part |
| Backwash never runs clear | Bed saturated | Change the sand |
Most residential beds get five to seven years. A pool with heavy bather load and a lot of sunscreen gets fewer.
Telling worn media from dirty media
Clean it properly and record the pressure. If a cleaned filter no longer returns to anywhere near its original clean number, the media is finished, not dirty. That single test saves an enormous amount of guessing — and it is why the clean pressure written on the tank is the most useful number on the pad. If the water is still dull after a real clean, the fault is upstream: check flow and filtration rate before you buy anything.