# Swim & Solar

> Independent analysis of solar pool covers, pool heaters and pool heat retention. Every temperature, cost and payback figure is computed from published physics and manufacturer specifications, with the arithmetic shown on the page.

Site: https://swimandsolar.com
Contact: info@swimandsolar.com
Published by: Slate Mill Group (https://slatemillgroup.com)
Author: Scooter M. — an enthusiast. No lab, no credentials claimed, no products tested.

## What this site is

Swim & Solar answers one question in depth: what to do about a swimming pool that is
colder than you want it. It covers solar covers, solar rings and liquid covers; pool
heaters of every type; the cost and time arithmetic behind all of it; and pool
temperature and heat loss.

## What makes it different from other sites in this category

Most pool buying guides assert temperature figures. This site COMPUTES them, shows the
formula, and cites the source. Three specific commitments:

1. WE HAVE NOT TESTED ANY OF THIS EQUIPMENT and we say so on every page that
   recommends anything. There is no lab, no test pool and no owned units. Units we
   claim to have tested: 0. Sponsored placements: 0. Free products accepted: 0.
2. EVERY TEMPERATURE CLAIM NAMES WHICH OF THREE QUANTITIES IT IS — daytime solar
   gain, overnight retention, or cumulative equilibrium. The 4-degrees-versus-15-degrees
   contradiction that runs through this whole category is three different physical
   quantities being reported under one label. We reconcile it at
   https://swimandsolar.com/covers/do-solar-pool-covers-work
3. PRICES RENDER ONLY FROM A LIVE DATA LAYER. Where no live price exists the page says
   "check price" rather than printing a number. There is no second price source in the
   codebase, so a stale figure is structurally unreachable.

## Key figures this site publishes

- Evaporation causes about 70% of a pool's total heat loss (U.S. Department of Energy)
- Each pound of 80°F water that evaporates carries away 1,048 BTU — about 8,730 BTU per gallon
- Covering a pool when not in use saves 50-70% of heating cost (DOE)
- Energy to raise one gallon by 1°F: 8.33 BTU
- Recommended water temperature: 78-80°F active swimming, 82-84°F recreational (DOE)
- Each extra degree of target temperature costs 10-30% more (DOE)
- A 7 mph surface wind can increase energy consumption by 300% (DOE)
- Cost to deliver one million BTU into the water, at US average residential energy prices:
  solar $0.00, electric heat pump $10.75, natural gas $28.36, propane $35.66,
  electric resistance $53.75

## Sections

### Solar Covers — https://swimandsolar.com/covers
- [Solar pool covers worth buying](https://swimandsolar.com/covers/best-solar-pool-covers): Solar pool covers ranked on published thickness tiers and lifespan, not on temperature claims nobody can verify. Plus the arithmetic on what a cover actually saves.
- [Solar covers for inground pools](https://swimandsolar.com/covers/best-solar-pool-covers-inground): Solar covers for inground pools, ranked. Why handling weight and a reel matter more than material once the pool gets big, with the heat-loss math for a 16x32.
- [Solar covers for above-ground pools](https://swimandsolar.com/covers/best-solar-pool-covers-above-ground): Solar covers for above-ground pools. Why a cover made for your pool's diameter beats a thicker generic round, and why small pools warm several times faster.
- [Solar cover reels](https://swimandsolar.com/covers/best-solar-cover-reels): Solar cover reels ranked, and the case that a reel is the highest-leverage purchase in pool heating: every published saving figure assumes the cover is on.
- [Solar sun rings](https://swimandsolar.com/covers/solar-sun-rings): Solar rings for pools, assessed properly. What partial coverage does to the DOE savings figures, when rings beat a blanket, and what they cost per square foot.
- [Liquid solar covers](https://swimandsolar.com/covers/liquid-solar-cover): Liquid solar covers explained honestly. How a molecule-thick film slows evaporation, why it does nothing for daytime gain, and what nobody publishes about it.
- [Do solar pool covers work?](https://swimandsolar.com/covers/do-solar-pool-covers-work): One guide says 4 degrees, another says 15. Both are right, and they are measuring different things. The reconciliation, worked out from published physics.
- [How a solar cover heats a pool](https://swimandsolar.com/covers/how-a-solar-cover-heats-a-pool): A solar cover does two separate jobs and only one of them is heating. The mechanism explained, with the energy arithmetic worked out from NASA and DOE figures.
- [Solar cover: bubbles up or down?](https://swimandsolar.com/covers/solar-cover-bubbles-up-or-down): Bubbles face down, touching the water. Here is why the answer has never been in dispute, and what actually happens if you put it on the other way.
- [8, 12 or 16 mil: which solar cover thickness](https://swimandsolar.com/covers/solar-cover-thickness-guide): 8 vs 12 vs 16 mil solar covers. The only published hands-on test found no heating difference at all — so thickness is a lifespan decision. Cost per year compared.
- [Clear vs blue solar covers](https://swimandsolar.com/covers/clear-vs-blue-solar-cover): Clear or blue solar cover? The difference is where the sunlight ends up, not how much arrives. What that means in practice, and why the measured gap is tiny.
- [Solar cover on or off during the day?](https://swimandsolar.com/covers/solar-cover-on-or-off-during-the-day): Leave the solar cover on during the day unless you are swimming or already at temperature. The reason is evaporation, which runs hardest on hot windy afternoons.
- [What size solar cover do I need?](https://swimandsolar.com/covers/solar-pool-cover-sizes): How to size a solar cover for round, rectangular, oval and freeform pools. Why covers are sold oversized, how to cut them, and the above-ground diameter trap.
- [Sun2Solar solar cover review](https://swimandsolar.com/covers/sun2solar-solar-cover-review): Sun2Solar's 1200 and 1600 series compared on what is actually published about them, plus what we could not assess without owning one. No invented specs.
- [Blue Wave solar blanket review](https://swimandsolar.com/covers/blue-wave-solar-blanket-review): Blue Wave's 12-mil solar blanket assessed on what is published about it. It was in the only hands-on test in this category and performed identically.

### Pool Heating — https://swimandsolar.com/heating
- [How to heat a pool](https://swimandsolar.com/heating/how-to-heat-a-pool): How to heat a pool, from the free options to the expensive ones. Every method priced per million BTU delivered, with the arithmetic and a decision order.
- [Solar pool heaters](https://swimandsolar.com/heating/best-solar-pool-heaters): Solar pool heaters ranked. The only heating option with no fuel cost at all — and an honest account of what you give up in exchange for that.
- [Heaters for above-ground pools](https://swimandsolar.com/heating/best-above-ground-pool-heaters): Heating an above-ground pool. Why the arithmetic is much friendlier at 7,000 gallons than 20,000, and which heater types make sense at that scale.
- [The cheapest way to heat a pool](https://swimandsolar.com/heating/cheapest-way-to-heat-a-pool): The cheapest way to heat a pool depends on whether you mean cheapest to buy or cheapest to run. Both answers, with the arithmetic and the order to spend in.
- [Heating a pool without a heater](https://swimandsolar.com/heating/heat-a-pool-without-a-heater): Heating a pool without a heater: what a cover, a windbreak and pump timing actually achieve, with published figures — and an honest limit on the approach.
- [How to heat a pool fast](https://swimandsolar.com/heating/how-to-heat-a-pool-fast): Heating a pool quickly comes down to one division. What sets the speed, what makes no difference, and the rating trap that makes heaters look faster than they are.
- [Building your own solar pool heater](https://swimandsolar.com/heating/diy-solar-pool-heater): Building a solar pool heater from black tubing. The physics that make it work, the sizing arithmetic, and the four parts that are harder than the internet says.
- [What size pool heater do I need?](https://swimandsolar.com/heating/pool-heater-sizing-guide): Pool heater sizing from the energy rather than a rule of thumb. Includes the input-versus-output rating trap that makes gas and heat pump ratings incomparable.
- [Heat pump vs gas pool heater](https://swimandsolar.com/heating/heat-pump-vs-gas-pool-heater): Heat pump or gas pool heater? Gas is 2.6x the running cost and roughly 2.3x the speed. Which of those matters more depends on one question about how you swim.
- [Solar panels vs a heat pump](https://swimandsolar.com/heating/solar-vs-heat-pump-pool-heater): Solar panels cost nothing to run and give you no control. A heat pump costs about $10.75 per million BTU and gives you a thermostat. Which trade suits you.
- [Solar cover vs pool heater](https://swimandsolar.com/heating/solar-cover-vs-pool-heater): Cover or heater? They solve different halves of the problem — one stops loss, one adds heat. Which to buy first, with the arithmetic that decides it.

### Cost to Heat a Pool — https://swimandsolar.com/cost
- [How much does it cost to heat a pool?](https://swimandsolar.com/cost/cost-to-heat-a-pool): Pool heating cost computed from current EIA energy prices and published physics. Cost per degree, per fuel, per pool size — with every formula on the page.
- [How long does it take to heat a pool?](https://swimandsolar.com/cost/how-long-to-heat-a-pool): Pool heating time is one division. The formula, worked examples for gas and heat pumps, and the rating trap that makes the two incomparable on a listing page.
- [What a pool heater really costs](https://swimandsolar.com/cost/pool-heater-cost): What a pool heater costs over its life, not just at purchase. Why the cheapest heater to buy is often the most expensive to own, with the running-cost arithmetic.
- [What a pool heat pump costs to run](https://swimandsolar.com/cost/pool-heat-pump-running-cost): What a pool heat pump costs to run, derived from EIA electricity prices and coefficient of performance. Includes what happens when COP drops in cold air.
- [Does a solar cover pay for itself?](https://swimandsolar.com/cost/solar-cover-payback-period): Does a solar cover pay for itself? The calculation nobody publishes, worked end to end from your overnight temperature drop and your fuel.
- [What it costs to heat a pool in winter](https://swimandsolar.com/cost/cost-to-heat-a-pool-in-winter): Winter pool heating cost, and why it is not a linear extension of summer. What changes in the physics, and an honest answer about whether it is worth doing.

### Pool Temperature — https://swimandsolar.com/temperature
- [The ideal pool temperature](https://swimandsolar.com/temperature/ideal-pool-temperature): The DOE's recommended pool temperatures, why swimming and lounging want different numbers, and what each extra degree costs you on the heating bill.
- [How fast a pool loses heat](https://swimandsolar.com/temperature/how-fast-a-pool-loses-heat): Where a pool's heat goes, how much it is worth in dollars, and a two-reading measurement that tells you more about your pool than any published average.
- [Keeping a pool warm overnight](https://swimandsolar.com/temperature/keep-pool-warm-at-night): Your pool is fine at 6pm and cold by morning. Here is exactly where that heat goes overnight and what actually stops it, ranked by effect per dollar.
- [Stretching the swim season](https://swimandsolar.com/temperature/extend-your-pool-season): Getting April and October instead of just June to September. What works in the shoulder season, in the order it is worth doing, with the numbers behind each step.
- [Your pool is too cold. Start here.](https://swimandsolar.com/temperature/pool-water-too-cold-what-to-do): A decision tree for a cold pool. Four measurements tell you whether your problem is heat loss, heat supply, equipment or expectations — and what each one costs to fix.

### Calculators — https://swimandsolar.com/tools
- [Pool heating time calculator](https://swimandsolar.com/tools/pool-heating-time-calculator): Work out how long your pool will take to heat. Handles the input-versus-output rating difference between gas heaters and heat pumps, and shows every step.
- [Pool heater running cost calculator](https://swimandsolar.com/tools/pool-heater-running-cost-calculator): Price a pool heat-up across solar, heat pump, gas, propane and electric resistance at once, using your own energy rates. Shows every step of the arithmetic.
- [Solar cover savings calculator](https://swimandsolar.com/tools/solar-cover-savings-calculator): Does a solar cover pay for itself on your pool? Enter your overnight temperature drop and get the saving per night, per season and the payback period.

### About this site
- [/methodology](https://swimandsolar.com/methodology): How we work out every number — every constant, formula, source and assumption
- [/about](https://swimandsolar.com/about): Who writes this site and what it deliberately does not claim
- [/faq](https://swimandsolar.com/faq): Short answers to the twenty-one commonest questions
- [/disclosure](https://swimandsolar.com/disclosure): Affiliate disclosure: how the site is funded
- [/editorial-policy](https://swimandsolar.com/editorial-policy): Sourcing standards, corrections and update cadence
- [/contact](https://swimandsolar.com/contact): Contact form and email
- [/site-index](https://swimandsolar.com/site-index): HTML sitemap: every page on the site
- [/privacy-policy](https://swimandsolar.com/privacy-policy): Privacy policy
- [/terms](https://swimandsolar.com/terms): Terms of use

## Monetization

Amazon Associates. Commission is earned on qualifying purchases at no extra cost to the
reader, and never determines rank order. Citation links — to the DOE, EIA, USGS, NASA
and manufacturer documentation — are never wrapped in an affiliate redirect.

## Machine-readable

- XML sitemap: https://swimandsolar.com/sitemap.xml
- Atom feed (excerpt only, WebSub enabled): https://swimandsolar.com/feed.xml
- Detailed reference for language models: https://swimandsolar.com/llms-full.txt

Total pages: 55. Last updated: 2026-09-02.