In this article
Many owners treat pool chemistry as chlorine and nothing else. They add some every few days and double it when the water turns green. The problem is that pool water is a balanced system of linked values. Chlorine does not work properly when pH is off, pH will not hold when alkalinity is wrong, and hardness out of range either eats surfaces or coats them. In Riyadh, strong sun, high evaporation and dust shift these values faster than in milder cities. This article explains each value, what happens when it is neglected and how to build a simple testing routine that protects the water, the pool and the swimmers.
Chlorine: the first line of defence
Chlorine kills bacteria and algae and breaks down organic matter from sweat and lotions. What matters is not how much you add but how much free chlorine is in the water when you test.
When chlorine is low
- Algae and cloudy water appear quickly in summer.
- Bacteria thrive, raising the risk of skin and ear infections.
- Spent chlorine compounds form, causing strong smells and red eyes.
When chlorine is very high
- Irritated skin and eyes and dry hair.
- Faster wear of rubber seals and metals.
- Fading of paints and some finishes over time.
Sun is chlorine's enemy in Riyadh, because UV breaks it down quickly during the day. Many outdoor pools use a stabiliser in measured amounts, but too much stabiliser reduces chlorine effectiveness, so it should never be added without testing.
pH: the value that controls everything
After chlorine, pH matters most, and the suitable range is about 7.2 to 7.6. It is close to the natural pH of tears, so the water is comfortable and chlorine works efficiently.
Low pH (acidic water)
- Grout and plaster erode and roughen.
- Ladders and metal parts in the pump and heater corrode.
- Eyes and skin sting.
- Chlorine is used up quickly.
High pH (alkaline water)
- Chlorine loses much of its effectiveness even at a reasonable level.
- Cloudy water and scale on tiles and the waterline.
- Scale builds up inside the filter, pipes and heater, reducing efficiency.
Total alkalinity: the buffer for pH
Alkalinity acts as a buffer that stops pH swinging. When it is low, pH jumps with every chlorine dose, rainfall or busy day, and you end up correcting pH daily for nothing. When it is high, pH becomes stubborn and hard to bring down. The practical rule is to adjust alkalinity first, then pH, then chlorine. This order saves chemicals and wasted effort.
Hardness, minerals and evaporation
Hardness measures calcium in the water. In hot regions, evaporation keeps concentrating minerals because water leaves and minerals stay, then top-up water brings more.
- High hardness: hard white scale on the waterline and inside heaters and pipes, and a tendency to cloudiness.
- Very low hardness: the water becomes aggressive and pulls calcium from grout and plaster, eroding them.
If your source water is hard, or the pool water has not been renewed for a long time, partial water replacement is sometimes the simplest way to restore balance, provided it is done in a planned way.
The cumulative effect on the pool
| Part | Effect of long-term neglect |
|---|---|
| Grout and tiles | Erosion, gaps, stains and waterline scale |
| Paint and plaster | Fading, chalking and roughness that holds algae |
| Pump | Seal wear, leaks and motor overheating |
| Filter | Clumped sand or scaled cartridges |
| Heater or chiller | Scale or corrosion on the heat exchanger |
| Metals | Rust and stains spreading to tiles |
| Swimmers | Eye and skin irritation and repeated infections |
For the financial side of this damage, read the hidden cost of neglecting water chemistry.
A simple testing routine for Riyadh
- Chlorine and pH: several times a week in summer, less in winter, and always after heavy use or a sandstorm.
- Alkalinity: periodically and after any large pH correction.
- Hardness and stabiliser: less often, and after large top-ups.
- Keep a log of readings and products added. It reveals patterns, such as pH rising after a particular chlorine product.
- Dose correctly: add products in the evening, spread or pre-dissolve them as instructed, with the filter running.
When to call a specialist
If readings will not hold despite correction, the water clouds again within days, stains and scale will not shift, or the pool has been neglected for a long time, ask for a full check. A technician can tell whether the issue is chemistry alone or the filter and circulation, and whether the water needs correcting or partial renewal.
Quick summary
- Chlorine alone is not enough. Balance is the foundation.
- Adjust alkalinity, then pH, then chlorine.
- Keep pH at about 7.2 to 7.6.
- Sun and evaporation shift values quickly, so test more in summer.
- A simple log saves chemicals and problems.
Frequently asked questions
Why is my water still cloudy after adding lots of chlorine?
Usually because high pH is weakening the chlorine or the filter is clogged. Correct alkalinity and pH, clean the filter, then adjust chlorine.
What is the right pH for a pool?
About 7.2 to 7.6. In this range the water is comfortable for eyes and skin, chlorine works efficiently and corrosion and scale are reduced.
Does a strong chlorine smell mean the water is clean?
Usually the opposite. The smell comes from spent chlorine combined with sweat and dirt, and it means the water needs treatment.
Why does a white line form at the waterline?
High hardness and pH combined with constant evaporation. Balancing the water and cleaning the waterline regularly reduce the scale.
