Common Pool Maintenance Mistakes

Introduction

Maintaining a pool may seem simple, but the reality is that many owners make mistakes that, while seemingly insignificant, end up causing serious problems – green water, damaged equipment, high repair costs and even health risks. The good news is that most of these mistakes are easily avoidable with proper knowledge.

In our experience in Margem Sul, we see the same problems repeatedly. From pools in Aroeira where chlorine is added at the wrong time, to condominiums in Seixal where filters go months without maintenance, the mistakes are surprisingly common – even among experienced owners.

This article identifies the most frequent pool maintenance mistakes, explains why they're problematic and, most importantly, how to avoid them. Knowing these mistakes can save you hundreds or thousands of euros in repairs and chemicals.

Chemical Treatment Mistakes

Mistake 1: Not Testing Water Regularly

The most common and most damaging mistake:

Why it's a mistake:

• Problems develop without visible symptoms
• By the time you notice cloudy water, it's too late
• Corrections cost more than prevention
• Wrong pH nullifies chlorine's effect

Solution:

• Test pH and chlorine 2-3x/week in summer
• Test weekly in winter
• Use strips or drop kit (more accurate)
• Record results to identify patterns

Mistake 2: Adding Chlorine During the Day

A classic mistake that wastes product:

Why it's a mistake:

• UV rays destroy chlorine rapidly
• Margem Sul sun is particularly intense
• You're literally throwing money away
• Pool is unprotected at night

Solution:

• Always apply chlorine after sunset
• Let it work overnight
• Use stabilised chlorine (with cyanuric acid) if applying during day
• Consider automatic night-time dosing

Mistake 3: Ignoring pH

Many focus only on chlorine:

Why it's a mistake:

• Chlorine becomes ineffective at high pH
• Wastes chemicals (needs much more chlorine)
• Causes skin and eye irritation
• Damages equipment (low pH)
• Promotes scaling (high pH)

Solution:

• Adjust pH BEFORE adding chlorine
• Always maintain between 7.2-7.6
• Check alkalinity (stabilises pH)
• Correct deviations immediately

Mistake 4: Chemical Overdose

"If a little is good, more is better" – wrong:

Why it's a mistake:

• Wastes products (money)
• Causes secondary imbalances
• Can damage lining
• Causes swimmer irritation
• Some excesses are difficult to correct

Solution:

• Always follow recommended dosages
• Calculate based on actual volume
• Test before and after applying
• Less frequent is better than overdose

Filtration Mistakes

Mistake 5: Insufficient Filtration

Cutting filtration time to save electricity:

Why it's a mistake:

• Stagnant water promotes algae and bacteria
• Chemicals don't circulate evenly
• Particles aren't removed
• €20/month savings can cost €200 in treatment

Solution:

• Minimum 8 hours in summer
• Divide into 2-3 periods if needed
• Increase after rain or intensive use
• Use variable speed pump for efficiency

Mistake 6: Not Backwashing

The filter needs regular cleaning:

Why it's a mistake:

• Clogged filter doesn't filter
• Increases system pressure
• Strains the pump (wear)
• Can damage the filter
• Water stays cloudy despite correct chemicals

Solution:

• Backwash when pressure rises 0.3-0.5 bar above normal
• Minimum fortnightly in summer
• Check sand condition (3-5 years)
• Clean pre-filter basket weekly

Mistake 7: Old Filter Sand

Sand doesn't last forever:

Why it's a mistake:

• Sand compacts and loses effectiveness
• Creates channels where water passes without filtering
• Can calcify (turning to stone)
• Backwash no longer helps

Solution:

• Replace sand every 4-5 years
• Consider filter glass (lasts 10+ years)
• Check visually if possible
• Note if backwash no longer improves the situation

Physical Maintenance Mistakes

Mistake 8: Not Brushing Walls

Vacuuming isn't enough:

Why it's a mistake:

• Biofilm (invisible bacteria layer) adheres to surfaces
• Algae starts on walls before becoming visible
• Vacuum doesn't remove adhered biofilm
• Chemicals don't penetrate biofilm

Solution:

• Brush walls weekly
• Use brush appropriate for your finish
• Focus on low-circulation areas
• Brush BEFORE vacuuming

Mistake 9: Incorrect Water Level

Seems trivial but causes serious problems:

Why it's a mistake:

• Pump can burn without water
• Skimmer doesn't remove leaves and insects
• Affects circulation and treatment
• Can permanently damage equipment

Solution:

• Check level weekly
• Maintain at mid-skimmer
• Compensate for evaporation (summer: 2-5cm/week)
• Watch after heavy rain

Mistake 10: Ignoring the Waterline

The most neglected area:

Why it's a mistake:

• Focus for bacteria and algae
• Dirty appearance even with clean water
• Stains become permanent
• Attracts insects

Solution:

• Clean waterline weekly
• Use specific product (not household detergent)
• Sponge or magic eraser
• Prevent with "pool-friendly" sunscreens

Seasonal Mistakes

Mistake 11: Rushed Spring Opening

Rushing to open the pool causes problems:

Correct procedure:

1. Clean thoroughly while empty
2. Check all equipment
3. Fill and circulate for 24h
4. Test all parameters
5. Adjust pH first
6. Adequate initial shock
7. Filter 24-48h continuously

Mistake 12: Inadequate Winterisation

Closing the pool badly multiplies spring work:

Correct procedure:

1. Deep cleaning
2. pH adjustment (7.0-7.2 for winter)
3. Super-shock
4. Long-lasting algaecide
5. Lower level (below jets)
6. Protect equipment
7. Install cover

Equipment Mistakes

Mistake 13: Ignoring Strange Noises

Warning signs that get ignored:

Why it's a mistake:

• Small problems become big ones
• Repair costs 10x less than replacement
• May be electrical hazard
• Can damage other components

Solution:

• Investigate any new noise immediately
• Switch off if noise is concerning
• Call technician before major damage
• Annual preventive maintenance

Mistake 14: Running Pump Dry

Even seconds can cause damage:

Common causes:

• Low water level
• Pre-filter leak
• Valve closed
• Suction blockage

Solution:

• Check level before starting
• Ensure water is in basket
• Install dry-run protection
• Never leave pump running without initial supervision

Common "Economy" Mistakes

Mistake 15: Using Household Products

Trying to save with substitutes:

Why it's a mistake:

• Household products have additives
• Inadequate concentrations
• Can create foam
• Can stain or damage
• False economy (uses more product)

Solution:

• Always use pool-specific products
• Buy in bulk for better price
• The €20 "saving" can cost €200 in corrections

Mistake 16: Not Having Backup Products

Running out of chemicals at a critical moment:

Essential products in stock:

• Chlorine (minimum 2 weeks)
• pH reducer
• Algaecide
• Flocculant
• Test kits

Summary Table: Cost of Mistakes

Prevention Checklist

Daily (2 minutes)

• [ ] Check water appearance
• [ ] Remove floating debris
• [ ] Confirm pump is running

Weekly (30 minutes)

• [ ] Test pH and chlorine
• [ ] Check water level
• [ ] Clean skimmer and pre-filter baskets
• [ ] Brush walls and stairs
• [ ] Clean waterline

Fortnightly (1 hour)

• [ ] Vacuum bottom
• [ ] Backwash if needed
• [ ] Test alkalinity
• [ ] Check equipment

Monthly (1-2 hours)

• [ ] Complete test (including stabiliser)
• [ ] Equipment inspection
• [ ] Clean filter (if cartridge)
• [ ] Check seals and gaskets

Frequently Asked Questions

What's the most expensive mistake to make?

Letting the pump run without water. Even a few minutes can destroy a mechanical seal (€100-200 to repair) or burn out the motor (€400-1,000 to replace). Always check water level before starting the pump.

Why does my pool turn green even with high chlorine?

Probably the pH is too high (above 7.8). At high pH, chlorine loses effectiveness – you can have 3 ppm chlorine and it not working. Correct pH first, then chlorine will be effective.

How many filtration hours are really needed?

In summer, minimum 8 hours for family-use pools. The rule is that all water should pass through the filter at least once per day. For a 50m³ pool with a 10m³/h pump, that means 5 hours minimum, but 8 is recommended for safety margin.

Is it true I can use supermarket bleach?

Not recommended. Household bleach contains additives (fragrances, thickeners) and has low concentration (4-5% vs. 12-15% for pool chlorine). You end up using more, introducing unwanted chemicals and may cause foaming.

When should I call a professional?

Whenever: water stays green after treatment, there are strange equipment noises, there are visible leaks, the problem persists after two correction attempts, or for annual preventive maintenance (start of season).

Conclusion

Most pool problems result from avoidable mistakes. The three fundamental principles are:

• Test regularly – Problems identified early are easy and cheap to fix
• Follow dosages – More isn't better; respect instructions
• Consistent maintenance – 30 weekly minutes prevents hours of corrective work

Avoiding these common mistakes can save you hundreds of euros per year and ensure a pool always ready to use. Prevention is always cheaper than correction.

If you need professional help with your pool in Margem Sul, ManutençãoPiscinas is here to help. Contact us for a no-obligation quote.