Hot tub water care, without the confusion

Water care is the part of hot tub ownership people worry about most beforehand and think about least afterwards. Once you have a routine it takes about ten minutes a week. The difficulty is almost entirely in the first month, while the vocabulary is still unfamiliar.

The three numbers

Everything comes down to three readings, and they matter in a specific order.

**Alkalinity** is the one to set first, even though it is the one nobody has heard of. It acts as a buffer that keeps your pH stable. If alkalinity is wrong, your pH will swing wildly no matter how much you chase it, and you will spend a fortnight wondering why nothing you add seems to stick. Set this first, then move on.

**pH** is how acidic or alkaline the water is. Too low and it becomes corrosive to the spa's components and irritating to skin. Too high and your sanitiser stops working properly and the water goes cloudy. This is the one to check most often.

**Sanitiser** — chlorine or bromine — is what actually keeps the water safe. Chlorine acts faster and is cheaper; bromine is more stable at spa temperatures and gentler on the skin, which is why plenty of spa owners prefer it. Either is fine. Pick one and stay with it, because they do not mix.

A routine that works

Test two or three times a week with strips. Dip, wait, compare, adjust. It genuinely takes a minute.

Check and correct sanitiser before anyone gets in, especially after a gap of a few days.

Rinse the filter under a tap every couple of weeks, deep-clean it with a proper filter cleaner every month or two, and replace it when the pleats are permanently discoloured or misshapen. Filters are consumable — a tired filter is behind a remarkable number of “my water has gone strange” calls.

Drain and refill every three months or so, more often with heavy use. Fresh water resets everything and is far easier than fighting chemistry in water that has been in there since spring.

The mistakes almost everyone makes

**Adding too much, too fast.** Spa volumes are small, so chemicals act quickly. Add half of what you think you need, wait, then re-test. Overcorrecting in both directions is the single most common cause of a fortnight of frustration.

**Chasing pH while ignoring alkalinity.** Covered above, but it is worth repeating, because it accounts for most of the cases where somebody feels they are doing everything right and getting nowhere.

**Neglecting the cover.** Lift it and look at the underside occasionally. A cover that has absorbed water gets heavy, stops insulating, and can harbour growth that keeps recontaminating water you have just balanced.

**Getting in with lotions on.** Fake tan, moisturiser, heavy makeup and suncream all go straight into the water and straight onto the filter. A quick rinse before getting in does more for water clarity than any chemical.

When to stop and ask

Cloudy water that will not clear after balancing, a persistent smell, or foam that keeps returning are usually a filter or a water-age problem rather than a chemistry one, and the fastest fix is often a drain and refill. If it keeps coming back after that, something mechanical may be going on and it is worth a call rather than another trip to the chemicals shelf.

Nobody expects you to enjoy this part. But it is a ten-minute habit, not a hobby, and once it clicks you will stop thinking about it entirely.