Leisure Time Calcium Booster | Hardness Increaser
Leisure Time Calcium Booster is a calcium hardness increaser formulated for spas and hot tubs. It raises the calcium hardness level of your spa water into the safe range, protecting against the two problems that low-calcium water causes: foaming and equipment corrosion. The fast-dissolving formula mixes in quickly with the jets running, and a measured dose moves hardness predictably toward the 150–400 ppm target range.
Calcium hardness is the most overlooked of the four core water-balance readings — most owners watch sanitizer and pH closely while ignoring hardness entirely. That's a mistake. Water that's too soft (low in calcium) is chemically "hungry" — it tries to take calcium from wherever it can find it, which means leaching it out of your spa's equipment. Soft water etches plaster and acrylic surfaces, corrodes metal heater elements and jet hardware, and is one of the leading causes of persistent foaming that no amount of defoamer can permanently fix. Soft fill water is especially common for owners using water softeners, well water, or municipal supplies in soft-water regions.
Calcium Booster corrects the problem at its source. By raising calcium hardness into the proper range, the water becomes chemically "satisfied" — it stops pulling calcium from your equipment, foaming subsides, and the corrosive etching stops. Maintaining hardness in the target range is one of the simplest ways to extend the working life of the most expensive components in your spa, and a single 32 oz bottle treats a standard residential spa for an extended period.
Leisure Time®
Leisure Time® Brand FAQs
Can I use Leisure Time products in any brand of hot tub?
Yes. Leisure Time spa chemicals are formulated to work safely in every major brand of residential hot tub, including Hot Spring, Caldera, Sundance, Jacuzzi, American Whirlpool, Bullfrog, and others. They're also compatible with every common spa shell material — acrylic, vinyl, fiberglass, rotomolded plastic, and stainless steel.
Will Leisure Time chemicals work with my sanitizer system?
The Leisure Time line is built for universal sanitizer compatibility. Products work with chlorine, bromine, ozone, mineral cartridge systems (silver/copper), biguanide systems (Baqua Spa, SoftSoak), and salt-generated chlorine systems like the FreshWater Salt System. Specific product labels will note any exceptions.
Can I mix Leisure Time with pool chemicals or other spa brands?
We don't recommend it. Spa chemistry is sensitive, and mixing brands can lead to unpredictable interactions — cloudiness, foam, sanitizer interference, or staining. Leisure Time products are tested as a complete system; using them together gives you the most predictable results and the simplest weekly routine.
How long do Leisure Time products last in storage?
Most Leisure Time chemicals have a shelf life of 1 to 3 years when stored properly. Keep all spa chemicals in their original containers, sealed tightly, in a cool, dry, well-ventilated area away from direct sunlight, freezing temperatures, and other chemicals. Liquid products are most sensitive to temperature; granular products are more shelf-stable but should still be kept dry.
Are Leisure Time products safe for septic systems and drainage?
Yes — when spa water is properly diluted and drained according to local regulations, Leisure Time chemicals at residual levels are safe for typical municipal drainage. For homes on septic systems, drain spa water gradually over your lawn or landscape rather than dumping it all into the septic field at once. Always check local ordinances before draining.
How often do I need to drain and refill my spa when using Leisure Time?
Industry guidance is to drain and refill every 3 to 4 months for a typical 400-gallon residential spa, regardless of which chemical brand you use. Heavy use, lots of bathers, or high-temperature soaking can shorten that interval; light use can extend it. Regular use of Leisure Time clarifiers, filter care, and stain & scale products helps maintain water quality between fills, but no chemical regimen replaces a fresh refill on schedule.
About Leisure Time®
For more than 40 years, Leisure Time® has built spa-specific water care chemistry trusted by hot tub manufacturers, dealers, and homeowners across North America. Where pool chemicals are formulated for tens of thousands of gallons of cool, lightly used water, Leisure Time® products are engineered for the opposite extreme: small water volumes, sustained high temperatures, heavy bather loads, and powerful jet circulation. That combination puts dramatically more stress on water chemistry than a swimming pool ever sees, and it's why generic pool chemicals don't perform reliably in a spa.
The Leisure Time® line covers the complete water care picture — sanitization, water balance, clarity, stain and scale prevention, filter care, and spa surface care — and every product is designed to work together as part of the Simple Spa Care Program. That means no surprise interactions, no guesswork about what's compatible with what, and a predictable weekly routine that takes minutes instead of hours. The full Leisure Time® system works with chlorine, bromine, ozone, mineral cartridge, and biguanide sanitizing programs, and is safe for every common spa shell material.
Leisure Time® is manufactured in the USA and is one of the most widely recommended spa chemical brands in the industry — used by Hot Spring, Caldera, Sundance, Jacuzzi, American Whirlpool, Bullfrog, and many other major spa manufacturers as the dealer-recommended water care solution for their tubs.
