Method
How we score pool filters
Our Fit Score is not a gut feeling with a number attached. Each criterion reads a stated input, applies a fixed rule, and carries a limitation. Given the same input, you reach the same score. This is the whole rubric, published so you can check our work or run it yourself.
The idea
Most "best of" lists hand out a "Best Overall" badge and leave you to trust it. We would rather show the working. A filter earns its Fit Score from six criteria, each weighted by how much it matters to a real owner. The score is the weighted total out of 10. Because the rule for each criterion is fixed and public, the result is reproducible: two people with the same input land on the same number, which is the difference between a transparent score and a defensible one.
What the score is, and is not
Scores are a criteria-based assessment built from published specifications, product form factor, and brand parts support. They are not independently measured lab results. We do not bench-test filters, and we never present a score as a test result. Where an input is a manufacturer-stated figure, we say so, because a rated flow is a claim on a box, not a measurement from our bench.
The six criteria
Weights total 100 percent.
Theoretical turnover at rated flow
25% of the scoreInputManufacturer rated flow (GPH or GPM) and the pool volume it can turn over in 8 to 10 hours.
- This is a mathematical comparison using the manufacturer's rated flow, not a measured installation flow.
- 9 to 10: rated flow comfortably turns over a large volume (over 20,000 gallons) within 8 hours.
- 7 to 8: covers a typical mid-size pool (10,000 to 20,000 gallons) within 8 to 10 hours.
- 5 to 6: suited to a small pool (under 10,000 gallons), or needs a long turnover on a mid-size pool.
- Below 5: rated flow leaves even a small pool short of one daily turnover.
LimitationRated flow is a manufacturer figure, not an independently measured flow rate. Real delivered flow drops with plumbing length, fitting size, elevation, and a loaded filter.
Pool-size fit
20% of the scoreInputThe manufacturer's recommended pool-size range against the pool segment this roundup targets.
- 9 to 10: matches its target segment with headroom at the top of the range.
- 7 to 8: fits the segment but sits near the edge of its range.
- 5 to 6: marginal, or clearly oversized or undersized for the segment.
LimitationFit is judged against a segment, not your exact pool. Confirm against your own gallons before buying.
Maintenance
20% of the scoreInputCleaning method (rinse-and-replace cartridge, backwash sand, or DE) and its typical frequency.
- 8: sand, cleaned by occasional backwashing, low weekly effort.
- 6: cartridge, rinsed often and replaced periodically.
- 5: DE, finest filtration but the most involved routine.
LimitationFrequency depends on bather load, debris, and climate. This is the method's typical case, not a measurement of your pool.
Parts and support
15% of the scoreInputBrand parts-availability tier and how easily media and spares are sourced a few seasons on.
- 9: major brand with wide, long-term parts support (for example Hayward).
- 8: major brand, parts widely available (for example Intex).
- 6: value brand with thinner long-term parts support.
LimitationAvailability changes over time and by region. Check current stock before relying on it.
Water usage
10% of the scoreInputWhether routine cleaning discharges pool water.
- 9: cartridge, rinsed without discharging pool water.
- 7: sand or DE, backwashing discharges water each clean.
LimitationActual water use depends on how often and how long you backwash, and on local rules for discharge.
Setup and storage
10% of the scoreInputForm factor: plug-and-play pump-and-filter combo versus a larger separate tank system.
- 8 to 9: combo unit, tool-free or near tool-free setup, easy to store off-season.
- 6 to 7: larger tank-style system, more involved to install and store.
LimitationSetup ease is partly subjective and depends on your experience and site.
Worked example: flow
Flow is the one criterion with real arithmetic, so here it is in full. Take a combo unit rated at 2,800 GPH (the figure Intex encodes in the SX2800 model name):
- Source: manufacturer specification, from the model name.
- Input: 2,800 GPH rated pump flow.
- Calculation: 2,800 divided by 60 is 46.7 GPM. A 15,000 gallon pool turns over in 15,000 divided by (46.7 times 60), about 5.4 hours, comfortably under 8.
- Rule applied: covers a mid-size pool within 8 hours, so the 7 to 8 band.
- Limitation: 2,800 GPH is a rated figure, not a measured flow. Real flow is lower once plumbing and a loaded filter take their cut.
Where a model's rated flow varies by SKU and we cannot confirm it, we show the same method but flag the number to verify against your unit, rather than print a figure we have not checked. The arithmetic never changes; only the input does.
How to reproduce a score
- Read the input for each criterion off the product: filter type, form factor, brand, and the manufacturer's rated flow and pool range.
- Apply the rule band above to turn each input into a number from 0 to 10.
- Multiply each by its weight and add them up. That weighted total, out of 10, is the Fit Score.
If your inputs differ from ours, for example your specific model lists a different rated flow, your score will differ, and that is the point. The method travels; plug in better data and it still works.
Where the method stops
The Fit Score ranks how well a filter suits a pool on paper. It cannot tell you about a bad unit that slipped through quality control, a retailer's current price, or how a specific pump and plumbing run will change real flow. Treat it as a strong starting point, then confirm the rated flow and pool range against the exact model you are about to buy.
Pumps and cleaners
This rubric is for filters. Pumps and pool cleaners are judged on different things, flow at head and efficiency for pumps, coverage and filtration for cleaners, so they get their own rubrics rather than a filter score that would not mean anything. Until those are published, we say plainly on each product that a filter score does not apply.