Hot Tub Care Tips from Bob Lowry: Keep Your Spa Sparkling

Hot tub maintenance gets confusing fast because spa water chemistry is not the same as pool care. Hot tubs run hotter, hold far less water, and see heavy bather load, so sanitizer demand spikes in minutes. That is why the bromine vs chlorine debate matters less than understanding what each product does. Bromine is a reliable disinfectant at higher temperature and higher pH, and bromamines stay active without the strong “chlorine” odor people hate. But bromine has a key limitation: it does not oxidize the oils and wastes bathers bring in, like sweat, urine, deodorant, lotions, and sunscreen.

That missing oxidation is why many spas look fine and then suddenly smell or feel dull a day or two later. Without an oxidizer, bromine can kill germs but it cannot break down the contamination that feeds problems and creates odors. A practical routine is to add an oxidizer after you soak, often a non-chlorine shock (monopersulfate) or a chlorine-based shock. The challenge is there is no simple test that tells you exactly when oxidation is needed, so consistency beats guesswork. Leaving the spa circulating for a short period after dosing helps distribute sanitizer and burn off waste before it turns into a bigger cleanup.

Small volume is the other big factor. In a typical 250 to 400 gallon hot tub, tiny amounts of chlorine create measurable ppm, but that ppm can disappear quickly once people get in. A single bather can represent several grams of chlorine demand, and two people in a spa can burn through roughly 1 ppm of chlorine in about 15 minutes. That is why many successful routines combine a steady feeder system with supplemental dosing after use. Systems like bromine tablets, dichlor, or newer “frog” style cartridges can keep a baseline sanitizer present, while post-soak shock restores the water’s ability to stay clean between uses.

Many spa owners also ask about liquid chlorine, pH, and the fear of “mixing” products. A common myth says liquid chlorine automatically spikes pH or cannot be used to shock a bromine spa. In practice, liquid chlorine can be used effectively in hot tubs, and shocking a bromine spa with chlorine is a normal, workable option. What matters is maintaining safe sanitizer levels and understanding product roles: disinfectant for killing pathogens, oxidizer for breaking down bather waste, and balanced water to protect equipment and comfort.

UV sanitizer and ozone generators sound like a complete solution, but they are best viewed as supplements. UV only treats water that passes close to the bulb, and performance drops if the sleeve gets coated with oils or scale because the effective germicidal wavelength is disrupted. Ozone is a powerful oxidizer, yet it has a very short life in water, often seconds in spa conditions, so its benefits happen near the injection point. Because neither UV nor ozone guarantees whole-tub residual protection, you still need a primary sanitizer such as chlorine or bromine for person-to-person protection. Finally, even perfect chemistry cannot save exhausted water, so draining a hot tub every 90 days, or using a bather-load formula to set the schedule, remains one of the most effective spa water care habits for clear, comfortable, low-odor water.