Pool & Spa Calculators

No. A salt system makes its own chlorine instead of buying it in jugs or tablets, but the water still gets sanitized by chlorine, specifically hypochlorous acid and hypochlorite ion produced when a salt cell splits dissolved sodium chloride apart through electrolysis. The difference is where the chlorine comes from and how it's delivered, not whether it's present. Someone with a chlorine sensitivity should treat a salt pool the same as any other chlorinated pool.

Yes. A salt cell only handles chlorine generation; it does nothing for pH, total alkalinity, or cyanuric acid stabilizer, all of which drift on their own schedule regardless of how the chlorine got there. Skipping those tests because the generator is running is one of the most common reasons a salt pool develops cloudy water or scaling even with salt sitting exactly on target.

The main difference is how chlorine gets into the water: a salt system generates it continuously from dissolved salt, while a traditionally chlorinated pool needs chlorine added directly on a regular schedule, whether as tablets, liquid, or granules. Everything else, pH, alkalinity, stabilizer, filtration, and regular testing, works the same in both. A salt pool generally means less frequent chlorine purchasing, not less overall water chemistry management.

Yes, in most cases. Converting mainly means installing a salt chlorine generator and cell in the equipment pad's plumbing, then adding pool-grade salt to bring the water up to that generator's target ppm range, typically in the neighborhood of 3,000 to 3,500 ppm depending on the manufacturer. Existing plaster, tile, and metal fixtures are generally fine at a properly maintained target range, but check the pool builder's or equipment manufacturer's documentation for compatibility before converting.

Properly balanced saltwater pools run around 3,000 to 3,500 ppm, which is close to imperceptible to skin and far below seawater's roughly 35,000 ppm, so the water tends to feel softer and less irritating to eyes than a heavily chlorinated pool, particularly one where free chlorine has been allowed to run high. The feel comes from lower harsh chlorine odor and a steadier chlorine level, not the absence of chlorine itself.

Use length times width times average depth times 7.5 for a rectangular pool, or 3.14 times radius squared times average depth times 7.5 for a circular one, since a cubic foot of water holds 7.5 gallons. Average depth is the shallow-end depth plus the deep-end depth, divided by two. Irregular shapes like kidney pools are typically estimated using an adjusted width before applying the same per-cubic-foot conversion.

Dosing depends on the shock product's strength and your pool's actual volume, which is why manufacturers publish per-10,000-gallon guidance on the package rather than a single universal number. A routine weekly shock typically uses less product than a treatment for cloudy water or algae, which needs a heavier dose. Always calculate your true pool volume first, then follow the specific product label rather than a general rule of thumb, since formulations vary in strength.

There's no single fixed amount, because the right dose depends on your pool's volume, current total alkalinity, and the target pH drop, and different manufacturers' acid concentrations vary. Muriatic acid product labels give per-gallon dosing tables for this reason. Add small amounts, wait for full circulation, and retest before adding more, since overcorrecting pH is easier to do than undoing it once it's gone too low.

The same core targets apply, sanitizer level, pH, alkalinity, but a spa's much smaller volume and higher operating temperature mean chemical levels shift faster and need more frequent testing, often every session rather than weekly. Higher heat also breaks down chlorine and bromine faster, so spas commonly run on a bromine system or need more frequent sanitizer top-ups than a similarly sized pool would.

Every calculator publishes its formula in plain English and a worked example. That example is a test case: the build re-derives it against the live calculation and fails if the two disagree, so the number explained on the page is provably the number the tool produces.

Any value that is not pure arithmetic — a threshold, a rate, a conversion factor — is cited to its original source with a retrieval date. Rates change, so check the "last updated" date and the linked source for anything time-sensitive.