What is Chlorination and Do You Still Need It?

Short answer:

yes, you need a chlorine residual in every safe pool. The better your swimming pool filtration system and circulation, the less chlorine you need to do the same job. This article explains chlorination in one page, shows why traditional plant-room designs waste chemicals, and outlines how Desjoyaux's pipeless filtration system and pool liner change your day-to-day maintenance.

Chlorination in 90 seconds

Chlorination = adding a chlorine compound that forms free chlorine (HOCl/OCl–) in water. Free chlorine disinfects (kills microbes) and oxidizes (burns off organics). When it reacts with contaminants, it creates combined chlorine (chloramines) that cause odor/eye sting. Good operation keeps free chlorine within range and combined chlorine near zero.

You still need chlorination because only chlorine provides a measurable residual in the pool between filtration cycles. UV/ozone/AOP are add-ons; they don't replace a residual.

The only numbers that matter (practical working bands)

1. pH: 7.2–7.6
2. Free Chlorine (FC): 1–2 ppm indoor; 1.5–3 ppm outdoor
3. Combined Chlorine (CC): ? 0.2 ppm
4. Cyanuric Acid (CYA, outdoor only): 30–50 ppm
5. Alkalinity: 70–120 ppm
6. Calcium hardness: 200–400 ppm (liner pools tolerate lower scale risk)

Hold these bands consistently and most of “pool problems” disappear.

Why many pools “need so much chlorine”

Traditional plant-room layouts send water through long underground runs to a remote pump and filter. That creates friction losses and dead spots in the pool. Standard media filters miss fine particles. Outcome:

1. Chlorine is forced to oxidize what filtration didn’t catch.
2. Corners, steps, benches, and ledges become low-flow zones where algae starts.
3. Dosing is uneven; chloramines build; water smells; eyes sting.

You are not “using too little chlorine.” You are using too little effective filtration and circulation.

Methods of chlorination (choose like an operator, not a shopper)

1. Stabilized tablets (trichlor/dichlor): slow and convenient; watch CYA creep outdoors and dilute periodically.
2. Liquid chlorine (sodium hypochlorite): clean daily dosing and shock; store cool.
3. Calcium hypochlorite (granular): strong oxidizer; adds calcium; monitor hardness.
4. Saltwater chlorine generation (SWCG): still a chlorine pool; generates on site; maintain the cell.
5. Automated sensors + dosing pumps: tight control of FC/pH; excellent for indoor or high-use pools.
6. UV/ozone/AOP: reduce chloramines and oxidation load; keep a chlorine residual anyway.

Pick based on pool water treatment type (indoor/outdoor/terrace), bather load, and how much you want to automate.

What changes with Desjoyaux Pools

Integrated, pipeless filtration at the pool wall places skimming and return together, creating a strong surface sweep and directed flow. Fewer penetrations. No plant room. Short path. Better hydraulics.

1. More fine-particle capture ? fewer organics left ? lower chlorine demand.
2. Directed circulation ? fewer dead zones ? fewer algae starts.
3. Simpler swimming pool construction for rooftops/basements; easier upgrades.
4. PVC pool liner finish is non-porous ? reduced biofilm adhesion ? faster cleaning and steadier clarity.

You still run a chlorine residual, but you generally operate at the lower end of the range with fewer shocks and fewer odor spikes. That is what low-maintenance swimming pool actually means.

If this is your pool, do this

• Outdoor terrace, weekend use, dusty city
  1. CYA 30–40 ppm. FC 1.5–2.5 ppm. pH 7.3–7.5.
  2. Extend filtration hours Fri–Sun; shock lightly Sunday night if the pool was busy.
  3. Monthly: dilute 10–15% if CYA creeps above 50–60 ppm.
• Indoor basement lap pool, daily training
  1. FC 1–2 ppm. pH 7.3–7.5.
  2. Automate pH and chlorine if budget allows.
  3. Keep room air slightly warmer than water; maintain humidity control.
  4. Target CC ? 0.2 ppm; if higher, run an oxidizing shock and verify airflow.
• Garden pool under trees
  1. Increase filtration during shedding season.
  2. Maintain FC at top of band during heavy debris weeks.
  3. Brush steps/benches once weekly; leaf cover saves time and chlorine.

Troubleshooting in one table

How much chlorine do Desjoyaux pools typically need?

The target is set by safety and local standards; the demand drops because the system removes more debris and circulates better.
Practically, owners run steady clarity at 1–2 ppm FC indoors and 1.5–3 ppm outdoors with CYA in range. That’s less odor, fewer swings, and fewer “emergency” shocks.

Risks of over-chlorination (and how to avoid them)

1. Irritation and odor (chloramines).
2. Premature finish fade if you keep spiking FC.
3. Wasted spend.

Avoid by holding pH in range, controlling CYA outdoors, and making filtration do its share of the work. Over-chlorination is usually a system problem, not a discipline problem.

Minimal-effort operating plan

1. Test with a reliable drop-based kit: FC, CC, pH, TA, CH, CYA.
2. Log readings; small daily trims beat big weekend fixes.
3. Start with one volume turnover per day; increase during heat, dust, or parties.
4. Store chemicals cool and dated; rotate stock.

For high-use or indoor pools, automate pH and chlorine dosing.

Where Desjoyaux Pools fits into the decision

If you’re evaluating swimming pool contractors near me, ask three questions that predict swimming pool maintenance:

• How does your system sweep the surface and avoid dead zones?
• What fine-particle performance does your filter achieve, and at what flow rate?
• What residual targets (FC/CYA) do you design for in this climate, and how do you keep CC ? 0.2 ppm?

At Desjoyaux Pools integrated wall-mounted module and reinforced liner are designed to answer those questions with less complexity and lower day-to-day chlorine demand.

FAQ for Chlorination

Q1: Is chlorine necessary in all swimming pools?

A: Yes. Every pool needs a measurable residual for continuous protection, even if you add UV/ozone/AOP.

Q2: How is Desjoyaux’s system different from traditional chlorinated pools?

A: It integrates skimming, return, and filtration in one pipeless filtration system at the wall, improving flow patterns and fine-particle removal while removing the plant room. Better hydraulics and a non-porous liner reduce chlorine demand and routine effort.

Q3: What are the risks of over-chlorination?

A: Irritation, odor from chloramines, faster finish fade, needless cost. Keep pH in range, control CYA outdoors, filter properly, and dose precisely.