Free pool and hot tub calculators for volume, chlorine, shock, pH, salt, pumps and heaters, plus practical homeowner guides. Every formula and source is shown.https://poolowl.com/en-ushttps://poolowl.com/guides/cyanuric-acid-explained/https://poolowl.com/guides/cyanuric-acid-explained/Stabilizer stops sunlight from destroying chlorine, but it also raises the chlorine level your pool needs. How CYA works, good levels, and how to raise or lower it.Fri, 02 Oct 2026 00:00:00 GMThttps://poolowl.com/guides/hot-tub-electricity-cost/https://poolowl.com/guides/hot-tub-electricity-cost/What really drives a hot tub's electric bill, how to find your spa's tested standby watts, and worked monthly estimates for mild and cold weather.Fri, 02 Oct 2026 00:00:00 GMThttps://poolowl.com/guides/how-to-adjust-pool-ph/https://poolowl.com/guides/how-to-adjust-pool-ph/Why pool pH drifts up, how to bring it down with muriatic or dry acid, how to raise it, and why your alkalinity decides how much acid you actually need.Fri, 02 Oct 2026 00:00:00 GMThttps://poolowl.com/guides/how-to-close-a-pool/https://poolowl.com/guides/how-to-close-a-pool/When to close, how much chlorine to add, how far to lower the water, and how to protect pipes and equipment from freezing, in the order the work actually happens.Fri, 02 Oct 2026 00:00:00 GMThttps://poolowl.com/guides/how-to-shock-a-pool/https://poolowl.com/guides/how-to-shock-a-pool/How to shock a pool so it actually works. Find the right chlorine level for your stabilizer, choose a product, and hold the level until the job is done.Fri, 02 Oct 2026 00:00:00 GMThttps://poolowl.com/guides/pool-chemistry-basics/https://poolowl.com/guides/pool-chemistry-basics/What free chlorine, pH, alkalinity, CYA, calcium hardness and combined chlorine actually tell you, which ones matter most, and what order to fix them in.Fri, 02 Oct 2026 00:00:00 GMT