Why is My Pool Water Clear but Smells Strong?

A strong chlorine smell may indicate chloramines. Shock the pool to break them down and restore proper sanitation.

The Myth of “Too Much Chlorine”

Most pool owners think a strong chlorine smell means there’s too much chlorine in the water. But that’s usually not the case.

The real culprit is something called chloramines, byproducts formed when chlorine binds with contaminants like sweat, urine, body oils, or leaves.

Here’s what’s happening:

• Free chlorine (the active sanitizer) combines with waste in the water

• This creates combined chlorine, or chloramines

• Chloramines are what give off that strong chemical smell

• They also cause red eyes, itchy skin, and reduced chlorine effectiveness

So if your pool smells, it likely has not enough active chlorine, not too much.

Why Chloramines Build Up in Clear Water

You might wonder how the pool can look perfect but still have this problem. That’s because water clarity and sanitation aren’t always linked.

Reasons chloramines build up in seemingly clean pools:

• Not enough free chlorine to break down contaminants

• Heavy swimmer load or organic material

• Poor circulation or filtration

• Infrequent shocking or chemical maintenance

Chloramines float on the surface and linger, especially if water is stagnant. This can create that unmistakable smell even when the water looks fine.

How to Test for the Real Problem

To know if chloramines are the issue, test your pool for:

1. Free chlorine (FC): The amount of active, working chlorine

2. Total chlorine (TC): The sum of free and combined chlorine

Then calculate:

• Combined chlorine (CC) = TC - FC

If combined chlorine is higher than 0.5 ppm, it’s time to act.

Testing tips:

• Use a DPD test kit for reliable results

• Test in the early evening to account for daytime chlorine loss

• Test after peak pool use to see how much sanitizer is consumed

Step-by-Step: How to Fix Strong Pool Smell

You can’t mask or ignore the smell. You have to eliminate the chloramines causing it.

Step 1: Shock the Pool

Shocking adds a high dose of chlorine to oxidize chloramines.

• Use a chlorine-based shock like calcium hypochlorite or sodium hypochlorite

• Dose according to your pool size

• Aim for a free chlorine level that is 10 times your combined chlorine

For example:

• If CC is 0.8 ppm, raise FC to at least 8 ppm to reach breakpoint chlorination

• Shock at night to avoid UV breakdown

• Run pump and filter for at least 24 hours after shocking

Step 2: Improve Circulation

Proper circulation distributes chlorine evenly and prevents chloramine accumulation.

To improve circulation:

• Run the pump 8–12 hours a day

• Adjust return jets to push water across the surface

• Use a pool brush to stir up stagnant areas

• Add a pool fountain or surface aerator if needed

Every part of your pool should have active water movement.

Step 3: Clean the Filter

If the filter is dirty, it traps debris and allows organics to feed chloramine formation.

• Backwash sand and DE filters when pressure increases 8–10 psi above normal

• Deep clean or replace cartridges every month during heavy use

• Inspect for tears, worn O-rings, or clogs that slow flow

A clean filter is essential for effective sanitation and water clarity.

Step 4: Balance Your Pool Chemistry

Chlorine alone isn’t enough. Other elements of pool chemistry help it work efficiently.

Ideal ranges:

• Free chlorine: 1–3 ppm

• Combined chlorine: Below 0.5 ppm

• pH: 7.4–7.6 (low pH makes chlorine too reactive, high pH reduces effectiveness)

• Total alkalinity: 80–120 ppm (helps buffer pH swings)

• Cyanuric acid (CYA): 30–50 ppm (for protection from UV degradation)

Imbalances can make even adequate chlorine levels work poorly.

Step 5: Shock on a Routine Basis

One shock doesn’t fix everything. Chloramines can build back up without regular care.

How often to shock:

• Every 1–2 weeks during the summer

• After big pool parties or storms

• After long periods of inactivity

Rotate chlorine and non-chlorine shocks to reduce buildup of stabilizer and manage water chemistry more easily.

Habits That Prevent Chloramine Formation

Preventing chloramines starts with controlling what gets into the water.

Here are practical ways to stop problems before they start:

1. Have swimmers rinse before entering the pool

   • Removes sweat, lotions, sunscreen, and deodorant

2. Use a poolside shower

   • Especially helpful after workouts or hot days

3. Keep pets and food out of the water

   • Organic material increases chloramine formation

4. Use a pool cover when not in use

   • Prevents debris and bugs from entering the water

5. Skim and vacuum regularly

   • Clears out contaminants before they react with chlorine

6. Discourage urination in the pool

   • Urea reacts directly with chlorine to form strong-smelling compounds

These habits reduce chlorine demand and keep your sanitizer working where it’s needed most.

Additional Tools to Help Maintain Water Quality

Technology can make this process easier.

• Automatic chlorinators: Keep chlorine levels steady without manual dosing

• Saltwater systems: Convert salt to chlorine on a consistent basis

• Ozone or UV systems: Break down chloramines without adding chemicals

• Digital testers: Offer quick, precise chemical readings with minimal guesswork

Using the right tools saves time and improves your ability to catch issues early.

When to Call a Pool Professional

Sometimes persistent smell means something deeper is going on:

• Plumbing biofilms that protect bacteria and trap contaminants

• High stabilizer levels locking up free chlorine

• A failing salt cell that’s not generating enough chlorine

• Cracks or organic buildup in pool fixtures

If smell persists despite consistent care and correct chemistry, schedule an inspection.

Your pool’s strong smell is more than just unpleasant. It’s a sign that your water isn’t balanced and your sanitizer isn’t doing its job. The water may look clean, but without active chlorine and a well-maintained system, the clarity is misleading. With regular testing, proper shocking, and small daily habits, you can eliminate that sharp odor and enjoy a pool that’s not just clear, but also truly clean, balanced, and safe to swim in.