Hot tub care FAQ

Five: a total alkalinity increaser, a pH adjuster, a sanitizer (bromine tablets or dichlor granules), a shock, and test strips. On bromine, add a sodium bromide bank for the first fill. Everything else waits until a test says you need it. The full checklist.

Total alkalinity first, then pH, then calcium hardness if needed, then sanitizer, then shock. Alkalinity comes first because it buffers pH: correct pH while alkalinity is out of range and the pH drifts straight back. Why, in more detail.

pH 7.2 to 7.8 and at least 3 ppm free chlorine, both per CDC guidance for hot tubs.^[source] Total alkalinity 80 to 120 ppm and calcium hardness 150 to 250 ppm in an acrylic spa are industry consensus ranges. Bromine users target 3 to 8 ppm per product labels. The full chart.

Bromine for a tub used a few times a week, because it holds a residual for days at spa temperature and needs less attention. Chlorine for a tub used most days, because it acts faster, costs less per month and does not accumulate cyanuric acid. The full comparison.

Divide your tub volume in gallons by three, then divide that by the average number of bathers per day. The result is roughly how many days the water has left. A 400-gallon tub used by two people a day works out at about 66 days. The formula and what shortens it.

Almost always the filter. Cartridges clog with body oils rather than debris, and the decline is gradual enough that there is never a day you notice. Chemically soak the cartridge overnight rather than rinsing it, rinse thoroughly, refit and run a full filtration cycle. All five branches.

Cloudiness is a clarity problem, and the meaningful question is whether the water carries a sanitizer residual. The CDC gives at least 3 ppm free chlorine and pH 7.2 to 7.8 for hot tubs.^[source] If you cannot hold a residual, do not use the tub until you can. If anyone becomes unwell, that is a question for a doctor.

That smell is combined chlorine, or chloramines, which are the spent product of chlorine reacting with organics. It means too little effective chlorine, not too much. Shock the water to break the chloramines down and free chlorine will come back. How to shock properly.

Surfactants in the water: body lotions, deodorant, and above all detergent residue in swimwear. Defoamer collapses the bubbles in seconds and removes none of the surfactants, which is why the foam comes back. The four branches and the fixes.

Weekly as a default, plus after any heavy use. The schedule should follow bather load rather than the calendar: four people on a Saturday leave far more organic load than one person twice in the week. Which shock, and how long to wait.

Rinse weekly, soak in a chemical cleaner monthly, and deep clean at every water change. Rinsing alone kills a cartridge in months, because what clogs it is body oil rather than debris and water does not remove oil. The full routine.

Not a pleated cartridge. Dishwasher heat deforms the plastic end caps so they stop sealing, the detergent is aggressive toward the media, and the jets are aimed at plates rather than into folded pleats. Some ceramic spa filters are sold as dishwasher-safe by their manufacturer, which is a genuine exception for a different material. Vinegar, bleach and the dishwasher, answered.

Measure four things: outer diameter across the end cap, length of the media body excluding any handle or thread, the bottom fitting and its size, and whether the top is open, a handle, or closed with a loop. Those four identify almost any spa cartridge. The cross-reference table.

Roughly every twelve months on a rinse-weekly, soak-monthly routine with normal household use. Rinsing without ever soaking roughly halves that, and running two cartridges in rotation extends both well past a year each. The six signs it is finished.

Down. The bubble side faces the water, so the air pockets sit against the surface and cut evaporation while trapping a layer of warm air. Facing them up wastes the insulating layer and turns the blanket into a tray that collects debris. Blanket versus hard cover.

Measure the outside of the cabinet at its widest point for length and width, template the corner radius with a piece of card, decide the skirt depth down the cabinet side, and choose the fold direction to match your lifter. Take every figure twice. The full measuring guide.

Biofilm protects the organisms within it from disinfectant, which is what makes it a real problem rather than an unpleasant one. The CDC’s hot tub guidance is built around maintaining a disinfectant residual, and a tub whose plumbing is consuming that residual is not maintaining it.^[source] How to confirm and purge it.

It depends on your electricity rate, your climate, your tub’s insulation and how often you use it, so any single figure would be invented. Work it out as heater kW times hours run per day times 30, plus pump kW times filtration hours times 30, multiplied by your rate per kWh. The full arithmetic.