# PoolSolver

> Pool math, with the work shown. Every number is derived from a primary source (NIST, CRC Handbook, CDC Model Aquatic Health Code, PHTA standards where applicable, APHA Standard Methods, manufacturer specs, and peer-reviewed literature where relevant) and every formula is shown on the page that uses it.

## Inventory

22 calculators + 1 orchestration sub-hub across 4 connected clusters (chemistry, heating, pump & filter, water & filling). Each cluster has its own hub page; a master index lists everything flat. The sub-hub (saltwater-pool-maintenance) doesn't compute numbers itself — it routes across the salt-corner calculators with a personalized maintenance schedule and a sourced galvanic-corrosion dataset.

- [All Calculators (master index)](https://poolsolver.com/calculators/): The complete inventory of 22 calculators grouped by cluster, in the logical order an owner usually wants them. Each cluster section header links to its hub; the chemistry section also surfaces the saltwater-maintenance sub-hub.

## Pool Chemistry

- [Pool Chemistry Calculators (cluster hub)](https://poolsolver.com/pool-chemistry-calculators/): 11 calculators forming one connected system. Volume feeds the sanitiser arc (chlorine, salt, salt-cell sizing, saltwater-conversion-cost, CYA), the balance arc (pH, alkalinity, calcium hardness), the LSI integrator, and shock triage. Read in order, the calculators answer the owner's real question — is the water safe, comfortable, and not eating equipment. Includes the saltwater-maintenance sub-hub for salt-pool orchestration.

- [Pool Volume Calculator](https://poolsolver.com/pool-volume-calculator/): Gallons and liters for any pool shape — rectangle, round, oval (stadium), true ellipse, kidney, L-shape, and diving pools with a hopper. Uses the NIST-exact 7.48052 gal/ft³ conversion at full precision rather than the rounded 7.5 most calculators use; the 0.7% difference compounds into every chemistry and heating decision downstream. Volume is the denominator of the whole site — every dose, BTU, and turnover starts here.

- [Pool Salt Calculator](https://poolsolver.com/pool-salt-calculator/): Pounds, 40-lb bags, or kg of salt to bring your pool to your generator's target salinity from current ppm and volume. Brand presets sourced to each manufacturer's manual: Intex 3,000 ppm, Hayward 3,200 ppm, Pentair 3,600 ppm. Honest about the residual salt liquid chlorine leaves behind (~1.65 ppm per ppm FC dosed) and the cold-water false alarm cells report when conductivity drops — so your pool isn't actually at zero salt as often as the readout claims.

- [Salt Chlorine Generator Calculator](https://poolsolver.com/salt-chlorine-generator-calculator/): Sizes the salt cell you actually need, using sourced output ratings from Pentair IntelliChlor and Hayward TurboCell manuals. Corrects the trap behind most undersized cells: rated output is a 24-hour figure, so on a typical 12-hour pump schedule you get half the box number — the cell rated for your gallons usually can't keep up, and the right choice is a size up (which runs fewer hours and lasts ~1.4× longer). Honest about the ceiling: a big pool on short pump hours can exceed even the largest residential cell.

- [Saltwater Pool Conversion Cost Calculator](https://poolsolver.com/saltwater-pool-conversion-cost/): Itemizes the one-time cost to convert a chlorine pool to saltwater — salt generator unit + initial salt charge (about 534 lb / 14 bags for a 20,000-gallon pool) + install (DIY $0, or ~$400 with an electrician). Pairs with an honest payback by chlorine spend: a heavy spender ($800/yr) recoups in ~1.7 years, medium ($500) in ~3.2, light ($300) may not recoup at all — because saltwater is cheaper chlorine, not free chlorine (the cell wears out every ~5 years). The recurring-cell caveat is pinned on the page, not buried.

- [Pool Chlorine Calculator](https://poolsolver.com/pool-chlorine-calculator/): Exact dose for the four common chlorine products — liquid (with trade % chips for 6 / 8.25 / 10 / 12.5), trichlor 90%, dichlor 55.5%, and cal-hypo 65/73%. CYA-aware FC target — about 11.5% of your cyanuric-acid reading, not a flat 3 ppm — sourced from O'Brien, Morris & Butler (1974) on cyanurate-chlorine equilibria, with Wojtowicz's percentage rule for the practical form. The side-effect ledger is always shown: trichlor and dichlor deposit cyanuric acid, cal-hypo raises calcium, liquid leaves residual salt — so you see what each product adds before you dose.

- [Cyanuric Acid Calculator](https://poolsolver.com/cyanuric-acid-calculator/): Cyanuric-acid dose to raise (granular stabilizer with brand presets) or lower (partial-drain plan when one round can't reach target). Includes the FC-cost ledger — every CYA target carries a higher required free-chlorine level, sourced from the cyanurate equilibria, so the trade-off is visible before you stabilize. Honest about the one-way valve framing: CYA only leaves via dilution; the "CYA reducer" products on the market are sequestrants that don't actually remove CYA.

- [Pool pH Calculator](https://poolsolver.com/pool-ph-calculator/): Muriatic acid (with strength chips from 14.5% low-fume to the 31.45% 10-N anchor) or soda ash to put pH where you want it. The dose is driven by your total-alkalinity reading — TA is the buffer; acid converts bicarbonate to dissolved CO₂, which off-gasses and lets pH rebound while TA stays down. Explains the CO₂-hinge mechanism most pool advice misses (you're not failing to dose; you're chasing the rebound) — honest that the dose is TA-precise while the pH trajectory is direction-and-magnitude, never false-precise to a decimal.

- [Pool Alkalinity Calculator](https://poolsolver.com/pool-alkalinity-calculator/): Baking soda to raise total alkalinity, or the acid-down-air-up sequence to lower it without crashing pH. Matched-pair engine with the pH calculator: identical inputs return identical acid doses on both pages by construction. Honest about the "alkalinity increaser" products you find at pool stores — overwhelmingly just baking soda at a markup.

- [Pool Calcium Hardness Calculator](https://poolsolver.com/pool-calcium-hardness-calculator/): Calcium chloride dose to raise pool hardness, with the form gap exposed live — anhydrous CaCl₂ (default 94% purity) is about 25% denser per pound than the dihydrate flake, and the pure-compound molecular-weight ratio is closer to 32%; both shown distinctly, not averaged into one chart. Honest that no chemical lowers calcium — dilution is the only knob, and the "calcium reducer" products sold for it are sequestrants that mask scaling without removing calcium.

- [Pool LSI Calculator](https://poolsolver.com/pool-lsi-calculator/): The Langelier Saturation Index from the full continuous saturation equation, not a rounded lookup table. Includes the cyanurate correction most LSI calculators skip — high CYA flips a "balanced" verdict to "corrosive" because cyanuric acid pulls effective alkalinity down. Five-zone verdict (strongly corrosive / corrosive / balanced / scaling / strongly scaling) with the "which lever to fix" routing back to the chemistry spokes.

- [Pool Shock Calculator](https://poolsolver.com/pool-shock-calculator/): SLAM dose keyed to your CYA reading (40% of CYA), not the conventional flat "10 ppm" — which falls below the real shock zone for any pool with CYA above ~30. Two modes: SLAM for algae (sustained held campaign) and breakpoint for chloramines (10× combined chlorine, a single push). Honest about the no-chlorine-floor case — when CYA is so high that the required dose is heroic, the page leads with the drain recommendation, not the dose.

- [Saltwater Pool Maintenance (orchestration sub-hub — not a calculator)](https://poolsolver.com/saltwater-pool-maintenance/): The first non-calculator page on the site — an orchestration sub-hub, not a generic guide. Generates a personalized maintenance schedule from your pool's actual inputs (cell model, pump hours, climate, chemistry) by routing each maintenance line to the calculator that owns its number. Carries two things the calculators can't: a sourced saltwater galvanic series for pool metals (zinc → titanium, with the 10:1 anode-to-cathode area design rule; voltages deliberately omitted because they vary by reference electrode) and salt-pool-specific chemistry with explicit tier labels — Standard (MAHC) / Mechanism (electrochemistry) / Industry practice — so the epistemic status of every claim is visible rather than blurred.

## Pool Heating

- [Pool Heating Calculators (cluster hub)](https://poolsolver.com/pool-heating-calculators/): 4 calculators on one connected energy story — heater sizing, monthly running cost, evaporation loss, heat-up time. They share one thermal engine by construction, so a value computed on one page can't drift from the same value on another. The cluster's wedge is showing both the one-time heat-up cost AND the monthly maintenance cost side by side — most clone calculators quote only the one-time and miss the bill that actually shows up.

- [Pool Heater Size Calculator](https://poolsolver.com/pool-heater-size-calculator/): Heater BTU/hr sizing by the two-number method — volume drives the heat-up energy (first-principles physics), surface area drives the standing loss (engineering convention with a labeled error bar). A heated pool's biggest loss is evaporation (~60% of the total), which is why a pool cover is the strongest single lever — about 54,600 BTU/hr saved on a standard example. Reports a class range, not a fake-precise single BTU number.

- [Pool Heating Cost Calculator](https://poolsolver.com/cost-to-heat-calculator/): Heat-up cost + monthly maintenance cost across gas, propane, heat pump, and electric resistance, with editable fuel prices (they vary by region). The headline finding: a pool cover saves about $719/month on a typical gas-heated pool, so a $200 cover pays back in roughly 8 days. Honest about the shoulder-season heat-pump COP sag — the 5.0 COP at warm air falls to about 3.8 at colder air, which narrows but doesn't erase its advantage over gas.

- [Pool Evaporation Calculator](https://poolsolver.com/pool-evaporation-calculator/): Gallons-per-day evaporation from a vapor-pressure model (Magnus saturation pressure + a residential-calibrated mass-transfer coefficient), reconciled to the heater-sizing engine's lumped coefficient — same physics, two views. Optional "your actual water loss" input drives a leak-or-evaporation verdict: below 1.3× normal is fine, 1.3-1.75× routes to a bucket test, above 1.75× suggests a leak. Never declares a leak with certainty.

- [Pool Heat-Up Time Calculator](https://poolsolver.com/pool-heat-up-time-calculator/): Hours to reach your target temperature from current, given heater output and pool conditions. Honest about the can't-reach-target case — when heater output sits below the standing loss, the pool never arrives, so the page refuses to print a heat-up time and instead suggests a cover (often makes it reachable) or the next heater class. Reverse mode answers the planning question ("how warm will it be by Saturday morning?") most calculators skip.

## Pool Pump & Filter

- [Pool Pump & Filter Calculators (cluster hub)](https://poolsolver.com/pool-pump-filter-calculators/): 4 calculators that correct the industry's filtration story in sequence — run time, pump size, filter size, cost. Two physics insights most pool advice misses: one turnover filters about 63% of the water (the 1−e⁻ⁿ exponential mixing law, not 100%), and pump cost scales with the cube of flow rate (slow-and-long beats fast-and-short by a wide margin). Most residential pumps are oversized and run too long.

- [Pool Pump Run Time Calculator](https://poolsolver.com/pool-pump-run-time-calculator/): Real turnover hours and the two corrections to the industry story: exponential mixing (one turnover filters ~63%, not 100%, so "two turnovers" isn't twice the filtration), and the cube-law cost penalty (a pump running twice as fast costs eight times the electricity per gallon turned over). The "8 hours a day" rule of thumb is honest about being a rule of thumb — the page works out your actual turnover from your actual numbers.

- [Pool Pump Size Calculator](https://poolsolver.com/pool-pump-size-calculator/): The operating point your pump will actually deliver — found by bisection root-finding against the pump curve and the system head curve, not nameplate horsepower. Two diminishing-returns insights: bumping HP by 18% raises real flow by ~9% (paying for the bigger pump barely helps), while bumping pipe diameter by one nominal step raises flow ~15% with less power (the right upgrade is usually pipe, not pump).

- [Pool Filter Size Calculator](https://poolsolver.com/pool-filter-size-calculator/): Filter sizing where the integrity wedge is the 48× area spread between sand and cartridge at the same flow rate — both correctly sized, but the cartridge is doing 48× the filtration work per square foot. Bigger filter is genuinely better here: more area means slower face velocity, finer particle capture, longer cycles between cleanings. The page shows the area + face-velocity numbers so you see why a "save money" small filter usually costs more in cleaning frequency.

- [Pool Pump Cost Calculator](https://poolsolver.com/pool-pump-cost-calculator/): What your pump actually costs to run, with the cube-law cost reconciliation made honest: the textbook 75% variable-speed saving rounds down to about 60% in real installations, because the cube law applies to the friction part of the system head, not the static head — and most residential systems have meaningful static head (vertical lift to the equipment pad). Variable-speed still saves substantially; just not the textbook 75%.

## Pool Water & Filling

- [Pool Water & Filling Calculators (cluster hub)](https://poolsolver.com/pool-water-calculators/): 3 calculators on the water-as-a-physical-thing side — cost to fill, fill time, and round-pool gallons (manufacturer-published water capacities for standard above-ground pools). Two practical wedges generic content misses: the sewer-exemption money-saver (most utilities will waive the sewer charge on fill water because it never enters the sewer — about $140 saved on an average pool), and the bucket test (gpm = 300 ÷ seconds for a 5-gallon bucket, so the fill estimate is built on your hose, not a generic average).

- [Cost to Fill a Pool Calculator](https://poolsolver.com/cost-to-fill-a-pool/): Dollar cost to fill from volume + your local water rate + your local sewer rate. The wedge most cost calculators miss: pool fill water doesn't enter the sewer, and many utilities will waive the sewer charge if you ask. On a 20,000-gallon pool that's about $140 saved (water-only ~$100 versus water+sewer ~$240). The page shows both numbers side by side so the difference is visible by construction.

- [Pool Fill Time Calculator](https://poolsolver.com/pool-fill-time-calculator/): Hours and days to fill from volume + your hose's actual flow rate. The wedge: most owners don't know their hose flow, but they can measure it in thirty seconds with the bucket test (gpm = 300 ÷ seconds for a 5-gallon bucket — so a hose filling a 5-gallon bucket in 33 seconds is doing about 9 gpm). The estimate is built on your actual hose, not a generic average that could be off by half.

- [Round Pool Gallons](https://poolsolver.com/round-pool-gallons/): Manufacturer-published water capacities for round above-ground pools — Intex, Bestway, Coleman, 15 verified sizes by diameter and wall height. The sourced chart, not a formula, because a 52-inch-wall pool holds water to about 45 inches (per Intex's own spec) — so the full-cylinder math overstates capacity by about 15%. The prize insight: same nominal size, different brands hold different gallons (Intex 18×48 = 6,423 gal versus Coleman 18×48 = 6,092 gal — a 331-gallon gap from liner thickness and fill convention that no πr²h calculator can produce). Includes a measure-it-yourself mode for off-chart pools.

## About

- [About PoolSolver](https://poolsolver.com/about/): Author bio — Marko Visic, Bachelor of Physics (Faculty of Mathematics and Physics) and Master of Pharmacy (Faculty of Pharmacy), both at the University of Ljubljana — and the verified-or-omitted editorial standard applied to every page. Names the primary sources concretely: NIST and the CRC Handbook for physical constants; CDC Model Aquatic Health Code for chemistry operating ranges; PHTA / ANSI where applicable; APHA Standard Methods for the Examination of Water and Wastewater for the dosing-engine ppm convention; manufacturer engineering specs for equipment data; peer-reviewed literature where relevant (the chlorine page cites O'Brien, Morris & Butler 1974 on cyanurate-chlorine equilibria, with Wojtowicz's analyses in the Journal of the Swimming Pool and Spa Industry). Maps the dual credential explicitly: physics underwrites volume / heating / hydraulics; pharmacy underwrites chemistry / dosing / saltwater electrochemistry.

## Legal

PoolSolver is operated by Moving Data Systems d.o.o., a limited-liability company registered in Slovenia (Smolnik 62, 2342 Ruše).

- [Privacy Policy](https://poolsolver.com/privacy/): What the calculators themselves collect (none — they're stateless and set no cookies), how advertising delivered through Raptive uses cookies and identifiers via Google and other partners, the EEA / UK consent surface under the GDPR and Google's EU User Consent Policy, and the data-subject rights including the right to complain to the Slovenian Information Commissioner (Informacijski pooblaščenec).

- [Terms of Service](https://poolsolver.com/terms/): The canonical estimates disclaimer — the calculators provide engineering and chemistry estimates derived from primary sources, not professional water-treatment, electrical, plumbing, structural, or medical advice. The CC BY 4.0 reuse terms for the sourced reference datasets are the only datasets released under that licence; the rest of the site is the operator's. Governing law is Slovenia.

- [Contact](https://poolsolver.com/contact/): One inbox — info@poolsolver.com — for corrections to a calculation or source, CC BY 4.0 reuse and licensing, partnership enquiries, and data and privacy requests under the GDPR.

## Reuse

Reference tables on calculator pages are released under CC BY 4.0. Attribute PoolSolver and link back.