Above-ground pools
Above-ground pools play by their own rules on gear — smaller water, 115V power, a filter and pump that came in the box and were probably sized by price. They play by exactly the same rules on water: free chlorine for your CYA, five numbers in range, and nothing else. So this school is organised like the main one, holds every guide that applies to your pool, and marks the ones written only for above-ground pools.
Calculate
Exact doses and targets — no guessing, no overshooting.
Chemical dosing calculatorHow much of what to move any level — chlorine, pH, alkalinity, calcium, stabilizer, salt.Free · on-device📈 Pool TrackerLog every test, get each number judged against your pool's target + the exact dose, and watch the trends. Free, on-device, no account.Water balance calculator (LSI/CSI)Corrosive, balanced, or scaling? The one index that ties your five numbers together.Pool volume calculatorHow many gallons is your pool? Every dose starts here.Salt vs. chlorine cost calculatorIs a salt system actually cheaper for your pool?
Learn the basics
Start here if you're new. The whole of pool care in a few short reads.
Less Is More: The Whole of Pool Care in One IdeaStart here. The one idea that makes every other pool problem simple — and cheaper.How to Test Your Pool Water (and Why Strips Lie to You)Strips and store tests hide the two numbers that matter most. Here's how to read your water for real — and the one kit to own.The 5 Numbers That Matter (and Their Target Ranges)Target ranges for every level, plus the FC/CYA chart — the single most important table in pool care.How Chlorine and CYA Actually Work (the Science Behind the FC/CYA Chart)Why free chlorine has to rise with CYA — the hypochlorous-acid science behind the FC/CYA chart, plainly.Do I Still Have to Test a Salt Water Pool?A salt system makes chlorine, not decisions. Here's what you still test — and the two numbers salt quietly pushes out of range.
Myths, settled
The pool-store gospel, fact-checked. A little reality, so you stop buying bottles you don't need.
Myth, settledDo You Have to Shock Your Pool Every Week?No. 'Shock' is a chlorine level you reach for a problem — not a weekly product or ritual.Myth, settledAre Salt Water Pools Chlorine-Free?No. A salt pool IS a chlorine pool — the cell just makes the chlorine for you, from salt.Myth, settledDo You Need Phosphate Remover?For almost every pool, no. Enough chlorine kills algae no matter how many phosphates feed it.Myth, settledDo You Need Algaecide?No. Proper chlorine prevents algae. Skip routine algaecide — and avoid the copper ones entirely.Myth, settledDo You Have to Run Your Pool Pump 24/7?No. A few hours to skim and mix your chemicals is plenty — chemistry sanitizes the pool, not laps through the filter.Myth, settledIs a Copper or Mineral Pool Chlorine-Free? (Is Copper Safe in a Pool?)Copper kills algae, but it's not a sanitizer, it stains, and it never leaves. A 'mineral pool' just runs less chlorine — not none.Myth, settledCan You Use Bleach in a Pool Instead of Chlorine?Bleach is the exact same chemical as pool 'liquid chlorine,' just weaker. It works fine. The only catches are strength and cost — use plain unscented, and buy fresh.Myth, settledIs Pool-Store 'Alkalinity Up' Just Baking Soda? (Pool & Hot Tub)It's the identical chemical — sodium bicarbonate — at several times the price. Baking soda raises alkalinity, not pH. What it does, how much, and the hot-tub version.Myth, settledCan You Lower Alkalinity Without Lowering pH? The 'Acid Slug' MythAcid lowers pH AND total alkalinity — always, together. The 'slug' or 'acid column' trick doesn't spare your pH; it just risks etching your plaster. The real fix is acid, then aeration.
Fix a problem
Jump straight to what you're dealing with. Answer first, the why underneath.
Start here🩺 Diagnose My PoolPick your symptom, enter a couple of numbers, get the diagnosis + exact target + fix. The fast way in.My Pool Is Green — How to Clear It (the SLAM Method)Green, cloudy, or hazy water; algae on the walls or floor.Green but My Chemical Levels Look Fine?Algae or cloudiness, but your test (or the pool store) says chlorine is fine.Mustard Algae That Comes Back (When Levels Are Good)Yellow/mustard (or green-yellow) dust on shaded walls and floor that brushes away and returns.Are Pool Stores a Scam? The Honest AnswerYou leave the pool store with a cart of chemicals and a printout — every time.Strong Chlorine Smell and Burning Eyes? You Need More Chlorine, Not LessA strong 'chlorine' smell and red, itchy, burning eyes after swimming.My Pool Is Cloudy but Not Green — What's Going On?Milky, hazy, or dull water — but it's not green and you don't see algae.CYA Too High? Why Your Chlorine Quit (and How to Actually Lower It)Your chlorine 'reads fine' but does nothing — or the pool store told you the pool has 'chlorine lock.'How to Recover Your Pool After Wildfire Ash, Smoke, or a StormWildfire ash, heavy smoke, or storm debris just fouled your pool — gray or cloudy water, a chlorine that won't hold, and gunk settling on the bottom.Pool Stains, Scale & Scum: What Each Mark Is and How to Remove ItA brown stain, a white crust, a greasy waterline ring — four different marks, four different fixes. How to tell them apart, remove each (the cheap way), and keep them gone.Above-groundAbove-Ground Pool Losing Water: Find the Hole, and What Actually Patches ItYour above-ground pool level keeps dropping, or the ground on one side is soft, soggy or washing out.Green Hair and Straw Hair After Swimming: It Isn't the ChlorineHair turning green after swimming, or going dry, dull and straw-like through the season.
Seasonal & away
Closing, opening, and leaving town — the calendar jobs, done in order.
How to Prep Your Pool Before Vacation (So You Don't Come Home to Green)The leave-it-safe checklist — build a chlorine reserve, raise FC before you go, run the pump, cut the sun. Come home to clear water, not green.Above-groundHow to Close an Above-Ground Pool for Winter (Rigid Wall, Soft-Side, and Florida "Winter Mode")Rigid wall, soft-side, or Florida — three different winters. The water level every source argues about, what the air pillow actually does, and why clips and wrap don't stop wind.Above-groundAbove-Ground Pool Winter Covers and Air Pillows: Which Cover Fits Your Pool, and What the Pillow Is Really ForScrim or strap, solid or mesh, round or oval — and the air pillow's real job, which is not the one on the box.How to Store Pool Floats for Winter (What the Makers Actually Say)Clean, dry, check, roll, store dark. What Intex, SwimWays, Big Joe and FUNBOY actually tell you, the bleach and cold-garage arguments settled, and a Florida version.Above-groundHow to Open an Above-Ground Pool in Spring (Without Buying a Start-Up Kit)Reconnect outside the pool before you fill, prime by hand every time, a fresh cartridge, a look at the walls — then chlorine the same day. Skip the start-up kit.Year-Round Pool Chlorination in Florida (You Don't Close, You Shift)A Florida pool runs year-round — you dial chlorine demand up in summer and down in winter, you never truly close. The season-by-season plan for CYA, free chlorine, the salt cell, and pump hours.
Look it up
The charts, definitions, and how-it-works guides — grouped by topic, for when you just need the number.
Water chemistry
Pool pH: Why It Rises, and How to Actually Control ItPool pH almost always drifts up — that's normal outgassing, not a mistake. Here's why, what raises and lowers it (and what each does to alkalinity), the targets, and why LSI is the real boss.Water Balance: Is Your Pool Corrosive or Scaling? (LSI/CSI, Plainly)Your numbers can each be 'in range' and the water still corrode or scale. The one index that ties them together — plainly, no products.Borates in a Pool: What They Actually Do (and What They Don't)The closest thing to an easy button in pool chemistry — and it still isn't one. Borates hold pH steadier, keep scale off a salt cell, and stay put until water leaves the pool. What they do, what they don't (two claims we had wrong, corrected), and which of the two dosing routes is actually cheaper.When Is It Safe to Swim After Adding Chemicals?Wait times for chlorine, acid, shock, CYA and more — and the one test that actually decides it.How to Remove Metal Stains with Ascorbic Acid (the Full Procedure)Ascorbic acid lifts iron stains fast — but it moves the metal into the water, it doesn't remove it. The full ordered procedure + the sequester-or-it-comes-back catch.
Chlorine & salt
Above-groundSalt Water System for an Above-Ground Pool: Check the Warranty First, Then Pick the UnitThe pool's warranty decides this before the chlorinator does. Which makers void it, which allow it, the units sized for above-ground pools, and the salt, flow and winter rules from their own manuals.Salt Water Pool Chemistry: Why the pH Climbs, and What to Set the Cell AtWhy a salt pool's pH rises, why alkalinity is the lever and the cell setting isn't, and the targets that actually differ from a chlorine pool.Which Chlorine Should You Use? Ranked by What Else It Puts in Your WaterLiquid, tablets, cal-hypo, dichlor, salt — same sanitizer, different baggage. Ranked by what else each one adds to your water (and when to break the rule).Chlorine Alternatives for Pools: What Actually Replaces It (Salt, Ozone, UV, Ionizers, Bromine)Salt is chlorine. Ozone, UV, and mineral systems only reduce it — they carry no residual, so you still chlorinate. One system is truly chlorine-free (biguanide), and it's a downgrade for almost everyone.How Long Does a Salt Cell Last? (And How to Make Yours Last Longer)Rated in hours, not years — usually 3–7. Why the cell wears out, the real ways to make it last longer (oversize it, don't over-clean it), and how to tell when it's done.Why a Salt Pool Scales Faster — and How to Fix Calcium BuildupThe white crust on your salt cell and tile isn't the salt's fault — it's calcium and pH. Why a salt pool scales faster, and the step-by-step fix (no anti-scale bottle required).
Equipment & filtration
How Long Should You Run Your Pool Pump — and at What Speed?Two pools, two answers. If you add chlorine yourself the pump is a skimmer and a mixer; if you run a salt cell it is a chlorine machine and the sun sets the hours. Plus the rule nobody publishes: your minimum RPM is set by your equipment, not your pool.Sand & Cartridge Filter Maintenance: When to Clean, and When Not ToWrite down your clean pressure the day you service the filter — that single number is what makes every other rule here work. Then clean on pressure, not on the calendar, and understand why a slightly dirty sand filter filters better than a spotless one.Your Pool Filter Is a Pressure Vessel (And It Can Take the Lid Off)Filters run under real pressure and trapped air can launch the lid. The manufacturer's own procedure, and what to check before you open yours.Above-groundSand Filter vs. Cartridge Filter for an Above-Ground Pool: Which Do You Need?Cartridge for a small pool (simpler, finer, no backwashing); sand once you get bigger (the media lasts years). The crossover is around 10,000–12,000 gallons. The honest comparison, no upsell.Above-groundWhat Size Above-Ground Pool Pump Do I Need? (It's GPM, Not Horsepower)Sizing an above-ground pump is a flow (GPM) problem, not a horsepower one. Match the pump to your pool's gallons AND your filter's rated GPM — bigger HP filters worse, not better. The turnover math, the filter ceiling, and how to replace a dead pump.Sand vs. Glass vs. Filter Balls: What to Put in Your Sand FilterYour sand filter can run traditional sand, recycled glass, or poly-fiber filter balls. Glass is the upgrade most people should make; sand is the safe default; filter balls are the lightweight wildcard. The honest comparison.Pool Pump & Filter Troubleshooting: Won't Prime, High Pressure, Noises, No FlowA symptom-first troubleshooter — high pressure, no flow, won't prime, noises, drips, sand in the pool. The free fix first, the real part only when it's earned.Above-groundAbove-Ground Pool Pump Running but Not Pumping Water? Check These in OrderHums but moves nothing? Gravity feeds an above-ground pump, so check where it sits, the water level, the valves, trapped air, the basket and the hose clamps — in that order. And turn it off first.Heat Pump vs Gas Pool Heater: What Each Costs to Run, With a CalculatorHeat for about half the price, or heat five times faster. The running-cost math with the energy prices stated, how far a heat pump really falls in cool air, and the install quote that decides most purchases.Why Isn't My Pool Heating? (Heater Basics + the No-Heat Checklist)Which heater fits your pool, the no-heat checklist (usually a free fix), sizing, and the one move that cuts heating cost 50–70%.Do Solar Pool Lights Actually Work? (And Why Yours Is Dim Under a Screen Cage)Solar pool lights work, within limits worth knowing before you buy: expect an evening rather than all night, expect less under a screen enclosure, and expect placement to matter more than price. The honest failure modes and the fixes that cost nothing.
Pool build & materials
Above-groundAbove-Ground Pool Types: Easy Set vs. Metal Frame vs. Rigid Wall vs. Semi-IngroundEasy Set, metal frame, rigid wall, semi-inground. The wall type sets your depth, your install, and whether the pool can ever be buried. And the depth on the box is not the depth you swim in.Above-groundSemi-Inground Pools: What You Can Actually Bury, and What Changes When You DoThe inground look without inground money - if the pool is rated for burial. What changes underground: the depth limit is a seam, the level tolerance quarters, drainage becomes the thing that kills it, and bonding is not optional.Above-groundWhat to Put Under an Above-Ground Pool: Sand, Pads and Ground Prep for Every Shape and SizeSand, no sand, pad, cove, blocks under the legs — the wall decides, and the makers disagree with each other. Every manual's numbers, plus a sand and cove calculator for round, oval and rectangle.Above-groundAbove-Ground Pool Deck: The Four Rules Before the BoardsBuild it freestanding, make its edge the pool barrier, keep it off the pool and no higher than the wall — then pick composite or wood.
← Back to Pool SchoolThat is every guide that applies to an above-ground pool. The in-ground school is one click back, if you want to see what the other half of the hobby deals with.