Your filter is the one piece of pool equipment that decides whether the water looks clear or hazy — and in Florida it works harder than almost anywhere in the country. Pollen, oak debris, sunscreen oils, and the algae that our heat feeds every month of the year all end up in the filter. Cartridge, DE, and sand each trap that load differently, need cleaning on a different schedule, and fail in different ways. Here is how each one works, how often to clean it in Pinellas conditions, and how to tell a dirty filter from a broken one.
The three filter types and how each one works
Nearly every residential pool in Pinellas runs one of three filter types. The difference that matters most to you is how fine a particle each one catches, because that is what you actually see in the water.
- DE (diatomaceous earth) — finest.Grids coated in a fine powder catch particles down to roughly 1–5 microns. This is the clearest water you can get from a residential filter, which is why polished, glass-clear pools almost always run DE. Pentair Quad DE and the FNS Plus are common here.
- Cartridge — middle.Pleated fabric elements trap down to about 10–15 microns. Very good clarity, no backwashing, and the most popular new-build choice in Florida. Pentair Clean & Clear and Hayward SwimClear are the workhorses.
- Sand — coarsest.Water passes through a bed of graded sand that catches down to about 20–40 microns. Cheapest to buy and the lowest-fuss to run, but it will never polish water the way DE does.
How often to clean each in Florida
Northern pools get a break in winter. Ours do not. Year-round pollen, heat-driven algae pressure, and a longer swim season mean Florida filters load up faster and need attention more often than the manufacturer's national averages suggest.
- Cartridge:a quick hose-down of the pleats roughly monthly, plus a full overnight deep-soak every quarter. Most cartridge elements last 2–3 years before the pleats break down.
- DE: backwash and recharge with fresh DE whenever pressure climbs, then pull the grids for a full teardown and inspection once or twice a year. That annual teardown is the step almost everyone skips.
- Sand:backwash when pressure rises, and change the sand media every 5–7 years — sooner in hard Pinellas water, which cements the bed faster.
The one rule: clean by pressure, not by calendar
This is the single most useful thing to know about any filter. When you first clean or recharge it, write down the pressure the gauge reads with the pump running — that is your clean baseline. As debris packs in, flow drops and pressure rises. When the gauge sits 8–10 PSI above that clean baseline, it is time to clean, regardless of what the calendar says.
A filter running 8–10 PSI high is choking your circulation. Less flow means less chlorine mixing and turnover, and that is how a clear pool goes hazy or green mid-week even though the chemistry looked fine. Rising pressure and weak water clarity almost always trace back to the filter and the pump working against each other — a tired pump and a clogged filter compound, which is why we cover both in our pump repair guide.
How to actually clean each filter
Cartridge.Shut off the pump, relieve the air, and remove the element. Hose the pleats top to bottom at an angle, spreading each fold so you flush grit out of the bottom rather than driving it deeper. For the greasy gray film that a garden hose will not touch — sunscreen, body oils, and calcium — soak the cartridge overnight in a dedicated filter cleaner, or a dilute muriatic-acid solution for mineral scale. Rinse thoroughly and let it dry. Never soak a cartridge in bleach or let it dry with chlorine on it— it destroys the fabric fibers.
DE.Backwash for 2–3 minutes, then recharge through the skimmer with the correct number of scoops for your grid square footage — too little and the grids run bare and clog; too much and you cake the manifold. Once or twice a year, open the tank, pull the grid assembly, hose every grid clean, and inspect for tears and cracks before reassembling.
Sand.Set the multiport valve to backwash, run until the sight glass runs clear, then switch to rinse for 20–30 seconds to reset the bed before returning to filter. Every 5–7 years the sand itself wears smooth and channels, at which point it needs to be dug out and replaced with fresh pool-grade media.
Filter failures that ruin water clarity
A dirty filter clogs; a broken filter leaks debris straight back into the pool no matter how clean the water chemistry is. These are the faults we find behind stubbornly cloudy water:
- Torn or collapsed cartridge— a split pleat lets unfiltered water bypass the element entirely.
- Cracked DE grid or manifold— sends DE powder shooting back into the pool through the returns, leaving a fine gray haze on the floor.
- Channeled or clumped sand— water carves a path through the bed and stops filtering; hard water can cement it into a solid mass.
- Blown multiport spider gasket(sand and some DE units) — sends water partly to waste and lets dirty water bleed past the valve.
- Missing or broken air-relief— traps air in the tank, drops flow, and gives you a false-low pressure reading.
If your pool stays cloudy after the chemistry is dialed in, the filter is the prime suspect. We walk through the full diagnosis in why is my pool cloudy, but the short version is: balanced water plus a healthy filter clears in a day or two, and if it does not, something on this list is failing.
Which filter is best for a Florida pool
There is no single right answer, but there is a right answer for your priorities.
- Cartridge is the most popular choice in Florida for good reason: no backwashing means no wasted water, which matters during Pinellas watering restrictions and drought advisories. Excellent clarity with the least fuss.
- DE gives the clearest water, period. If you want that polished sparkle and do not mind an annual grid teardown, DE wins on looks.
- Sand is the cheapest to buy and the most forgiving to run, but it wastes water on every backwash and gives up the finest clarity.
Cost of a pro cleaning vs DIY — and when it is a broken filter
A DIY cartridge rinse or sand backwash costs you nothing but time and a little water. A cartridge soak adds the price of a jug of filter cleaner. A professional filter clean in Pinellas typically runs $75–$150 for a cartridge or sand backwash-and-inspect, and $120–$200 for a full DE grid teardown, because pulling, hosing, and inspecting every grid is genuinely tedious work.
The catch is that most homeowners do the easy monthly rinse and skip the quarterly deep-clean and the annual DE teardown — exactly the steps that keep the filter actually filtering. That is where a pro visit earns its keep: it catches a hairline grid crack or a worn cartridge before it turns your pool cloudy. When a cleaning does not drop the pressure back to baseline, or the water will not clear, the filter is no longer dirty — it is broken, and that is a repair, not a cleaning.
Pool Optics folds the pressure check and filter rinse into every weekly service visit, handles the quarterly deep-cleans and DE teardowns most owners skip through our deep-clean service, and diagnoses cracked grids, torn cartridges, and blown gaskets under equipment repair. Same CPO-certified tech every week, a photo report after every visit, and month-to-month with no contract.
Get your filter checked
If your filter pressure keeps climbing, your water will not clear, or you honestly cannot remember the last time the grids or cartridge came out for a real cleaning, let us take a look. Send a couple of photos of your filter and equipment pad through our quote form or call (352) 586-0364. Jacob is CPO-certified, fully insured, and services St. Petersburgand the rest of Pinellas plus west Hillsborough — we can usually tell you over the phone whether it is a cleaning or a repair.
Frequently asked questions
How often should I clean my pool filter in Florida?
Rinse a cartridge monthly and deep-soak it every quarter; backwash a DE or sand filter whenever pressure climbs, tear down DE grids 1-2 times a year, and replace sand media every 5-7 years. But the real trigger is pressure: clean any filter when the gauge sits 8-10 PSI above its clean baseline, not on a fixed calendar. Florida's year-round pollen and heat-driven algae load filters faster than northern pools.
What is the difference between cartridge, DE, and sand pool filters?
They differ in how fine a particle they trap. DE (diatomaceous earth) is finest at roughly 1-5 microns and gives the clearest water; cartridge sits in the middle at about 10-15 microns; sand is coarsest at 20-40 microns. DE polishes water best, cartridge wastes no backwash water, and sand is the cheapest and lowest-maintenance option.
When should I clean my pool filter instead of waiting for a schedule?
Clean it when the pressure gauge reads 8-10 PSI above the clean baseline you noted right after the last cleaning or recharge. A filter running that high chokes circulation, and reduced flow can turn a clear pool cloudy or green mid-week even when the chemistry tests fine.
How much does professional pool filter cleaning cost in Pinellas?
A cartridge or sand backwash-and-inspect typically runs $75–$150 in Pinellas, and a full DE grid teardown runs $120–$200 because every grid has to be pulled, hosed, and inspected. If a cleaning does not bring pressure back down to baseline, the filter is broken rather than dirty and needs repair, not another wash.
Does Pool Optics clean pool filters in St. Petersburg?
Yes. Pool Optics checks filter pressure and rinses the filter on every weekly visit, handles the quarterly deep-cleans and annual DE grid teardowns most owners skip, and diagnoses cracked grids, torn cartridges, and blown multiport gaskets. We are CPO-certified, fully insured, send a photo report every visit, and stay month-to-month with no contract. Call (352) 586-0364.