Pool maintenance for beginners: testing order and a weekly routine

Pool pH is kept between 7.2 and 7.8, with 7.4, the pH of human tears, regarded as the ideal set point; total alkalinity is targeted at 80-120 mg/L and calcium hardness at 200-400 mg/L. Free chlorine does the disinfecting, while cyanuric acid protects chlorine from sunlight and extends the half-life of the active chlorine residual by 4 to 6 times.

The most important information in the table is the correction order: alkalinity first, then pH, then calcium hardness. Alkalinity is the buffer for pH; pH corrected without a buffer drifts back within a day and the chemical is wasted. Cyanuric acid and hardness only ever rise; the only way to lower them is to drain part of the water and refill with fresh water.

The reason is pH. In water, chlorine forms hypochlorous acid (HOCl), and HOCl partly dissociates into the hypochlorite ion (OCl-); the pKa of this dissociation is 7.53. At pH 7.2 most of the chlorine is in the active HOCl form; at pH 8 most of it has shifted to the weaker OCl- form. The test kit shows the same figure in both cases; disinfecting power is decided by pH.

The second confusion is the chlorine smell. The smell does not come from free chlorine but from chloramines (combined chlorine), which chlorine forms with nitrogen-containing waste such as sweat and urine. Smell and stinging eyes are a sign of too little chlorine, not too much; the answer is to add chlorine, not cut it. Chloramines are broken down by superchlorination (shocking); a typical summer practice is shocking every two weeks to a target of 10 mg/L.

Filtration and circulation come before everything else: no chemical spreads evenly unless the pump runs at least one full turnover a day. Physical cleaning comes next; leaves on the surface and sediment on the floor add organic load to the water and consume chlorine. Testing and dosing follow cleaning; samples are taken while circulation is running and at least one turnover after a chemical dose.

The logbook is the backbone of the routine. Date, pH, free chlorine, combined chlorine, alkalinity, chemical added and quantity go on one line. Two weeks of records show how much chlorine the pool consumes per day and which way pH drifts; dosing is read from that log, not guessed.

As water passes through the filter sand it leaves the suspended particles behind; when the sand is loaded, inlet pressure rises and the filter is cleaned by backwashing. The one gauge a beginner needs to learn is the pressure gauge: note the pressure with a clean filter and backwash when it rises clearly. Backwashing sends water out of the pool; top the level back up to the middle of the skimmer mouth, otherwise the skimmer draws air and the pump runs dry.

The cleaning equipment list is short: a telescopic pole, a leaf skimmer, a pool vacuum or automatic robot, a wall brush, and a DPD tablet test kit or test strips. The DPD method measures free and total chlorine separately, and the difference between them is combined chlorine; test strips give a rough idea, while the DPD kit is used for the log. Choosing a pump and filter is the subject of separate articles; in the first season it is enough to use the existing equipment correctly.

At opening, the winter cover comes off, the surface and floor are cleaned, the level is topped up, and the filter and pump are checked and started; then the five values are tested, and alkalinity, then pH, then hardness are corrected and a shock dose is given. The pump runs continuously until the water clears. At closing the order is reversed: final test and balance, final shock, winterising liquid, lowering the level below the skimmer mouth, draining the pipework, and the cover.

Once the maintenance routine is in place, the operating side of the pool project is settled: testing order, weekly list and logbook. Automatic dosing and remote monitoring make this routine easier but do not replace it; automation tests the same five values and corrects them in the same order.