Blog: pool maintenance guides

Tool

Sep 30, 2026

Your town's tap water, and what it means for your pool

Tap water hardness, pH and chlorine in 13 towns south of Madrid, from official analyses, and how much calcium to add when filling.

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Regulations

Sep 29, 2026

How to read your pool chlorine label (and what it should never say)

Authorisation number, active substance, pictograms and H statements: what the tub really says and how to check in two minutes that the product is authorised.

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Safety

Sep 29, 2026

Hot tubs and spas: Legionella and Pseudomonas, what the rules require in Madrid

Warm bubbling water is ideal for Legionella and Pseudomonas. Legal limits, maximum temperature and the cleaning the rules require.

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Equipment

Sep 29, 2026

Variable-speed pool pump: is it worth it?

Why a pump that runs slower uses far less power: the cube law with simple numbers and which pools the switch makes sense for.

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Regulations

Sep 25, 2026

Community pool rules of use (printable sign)

The 9 rules in Decreto 99/2024, what else to display and a PDF sign.

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Maintenance

Sep 25, 2026

Pool maintenance contract: what it should include

What should be in writing so you can compare quotes without surprises.

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Water chemistry

Sep 25, 2026

Types of pool chlorine: which to use

Trichlor, dichlor, calcium hypochlorite or liquid: which suits you and why.

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Maintenance

Sep 25, 2026

Dogs in the pool: how they affect the water and filter

Hair in the filter, more chlorine used and how to compensate.

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Equipment

Sep 25, 2026

LED pool lights: replacement and electrical safety

Why LED pays off, what the electrical rules require and how to change it.

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Tool

Sep 5, 2026

Langelier Saturation Index (LSI) calculator

Find out with a single number whether the water is corrosive, balanced or scale-forming.

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Regulations

Sep 25, 2026

Is a lifeguard mandatory for my community pool? (Madrid)

Who needs one, how many by water surface and what happens during their break.

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Equipment

Sep 25, 2026

Pool pump losing prime: how to prime it

Why it happens, how to prime it step by step and where to find the air leak.

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Water chemistry

Sep 25, 2026

How to test chlorine and pH: strips, drops or photometer

Strips, drops or photometer: which to use, how to sample and common mistakes.

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Water chemistry

Sep 25, 2026

Flocculant or clarifier: which to use in your pool

Which to use for your filter and how cloudy the water is, and step by step.

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Season

Sep 25, 2026

Mosquitoes and bugs in the pool: how to prevent them

Where mosquitoes really breed and what to do without putting insecticide in the water.

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Regulations

Sep 25, 2026

Community pool log book (free template)

Who has to keep it, when to test, what to record and a free PDF template.

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Water chemistry

Sep 25, 2026

Shock treatment: when, how much and how to do it

What it is, when you need it, how to work out the dose and when you can swim again.

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Season

Sep 25, 2026

Saharan dust or muddy rain in your pool: what to do

Vacuum to waste, backwash and chlorine, in that order. You almost never need to drain it.

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Season

Sep 25, 2026

Your pool in a heatwave: how to stop it turning green

At 40 °C chlorine is used up in hours. What to watch so it doesn't turn green.

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Water chemistry

Sep 25, 2026

Yellow dust in the pool: pollen or mustard algae?

A simple test to tell them apart and how to treat each one.

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Equipment

Sep 11, 2026

Redox probe and pH probe: what each one is for

They measure different things, Redox measures effectiveness, not the amount of chlorine.

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Equipment

Sep 11, 2026

Mosaic tile, liner or fiberglass: which lining to choose

It's not just about looks, it directly affects how you need to care for the water.

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Equipment

Sep 11, 2026

Skimmer pool or overflow pool: the real differences

It changes maintenance, water consumption and budget.

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Maintenance

Sep 11, 2026

Pool maintenance calendar

What to do every day, week, month and season, with links to each detailed guide.

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Regulations

Sep 11, 2026

Documentation to open a community pool each year

The checklist of paperwork a community should have ready before opening.

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Equipment

Sep 11, 2026

The pool pump: how it works

The heart of the filtration system, its parts and the signs that something's wrong.

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Regulations

Sep 11, 2026

Dosing pumps: automatic dosing

With bathers present, dosing by hand stops being a legal option.

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Maintenance

Sep 11, 2026

Filter backwashing: when and how to do it

The exact steps, and why doing it too much makes filtration worse instead of better.

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Equipment

Sep 11, 2026

Heat pump: how much it extends the season

Raises the temperature 0.5-2°C a day, with 4-6 times the performance of a regular heater.

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Safety

Sep 12, 2026

Health risks of a poorly maintained pool

Ear infections, dermatitis, irritation... why the water's appearance doesn't always tell the whole story.

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Regulations

Sep 11, 2026

Decreto 99/2024: the new pool regulations in Madrid

Water checks, turbidity, lifeguards and the penalties if your community doesn't comply.

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Maintenance

Sep 11, 2026

Pool water leaks: how to detect them

The bucket test tells a real leak apart from normal evaporation in just 24 hours.

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Renovation

Sep 15, 2026

When to renovate your pool: the real warning signs

Recurring leaks, worn-out lining, growing cracks, the signs we use ourselves to make the call.

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Maintenance

Sep 11, 2026

The most common mistakes in pool maintenance

The mistakes that repeat most, season after season, and that explain most problems.

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Equipment

Sep 11, 2026

Robotic pool cleaner vs. manual cleaning: when is it worth it?

It's not about which system cleans better, it's about which routine fits you, and which areas still need a hand.

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Season

Sep 11, 2026

Pool thermal cover: what it's really for

Cuts evaporation by up to 95% and protects chlorine from the sun, much more than a simple heater.

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Safety

Sep 10, 2026

Safe storage of pool chemicals

Why you should never mix them, and what the regulations require of communities regarding the storage room.

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Water chemistry

Sep 9, 2026

Filter selector valve: what each position does

Filter, backwash, rinse, recirculate, waste and closed, and the order that actually matters.

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Water chemistry

Sep 9, 2026

Types of pool filter: filtration power compared

Sand, recycled glass, zeolite, cartridge or diatomaceous earth, which filters best and which suits which pool.

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Regulations

Sep 8, 2026

What health authorities require of a community pool (RD 742/2013)

Mandatory checks, the Control Logbook and documentation for the season opening.

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Water chemistry

Sep 8, 2026

Cloudy or brown pool water: why it happens

Filtration, calcium hardness or dissolved iron, different causes from green water, with different treatments.

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Water chemistry

Sep 7, 2026

Black algae in the pool: why regular treatment isn't enough

They're not really algae, but cyanobacteria with a protective layer that's very resistant to chlorine. What it really takes to get rid of them.

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Maintenance

Sep 7, 2026

Stains in the pool: why they appear and how to remove them

Not all stains are the same, metallic or limescale stains each need a different treatment. How to tell them apart.

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Water chemistry

Sep 7, 2026

Foam in the pool: why it appears and how to remove it

It almost always comes from soaps, sunscreens or a low-quality algaecide. Why it happens and how to fix it.

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Water chemistry

Sep 7, 2026

Calcium hardness: the water parameter almost no one watches

The fourth parameter that decides whether your water is corrosive or scale-forming, alongside pH, alkalinity and cyanuric acid.

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Water chemistry

Sep 6, 2026

Cyanuric acid (stabilizer): what it is and why not to overdo it

It protects chlorine from the sun, but too much does exactly the opposite of what it's supposed to prevent.

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Water chemistry

Sep 4, 2026

What does the chlorine % on the bottle mean?

A kilo of chlorine isn't always a kilo of chlorine. Why a 70% bottle and a 56% bottle don't perform the same.

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Water chemistry

Sep 4, 2026

What is PPM and why is it used to measure your pool?

It shows up on any test strip, but almost no one knows what it means. What parts per million are and why it's the industry's standard unit.

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Regulations

Sep 3, 2026

Mandatory professional certificate for community pools before 2027

From January 2, 2027, staff who treat the water in pools for public or collective use must hold the SEA757_2 Professional Certificate.

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Water chemistry

Sep 2, 2026

Green pool water: why it happens and what to do

One of the most common summer emergencies. Why algae appear and what to do the moment you see green water.

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Water chemistry

Sep 2, 2026

Why does my pool smell so strongly of chlorine?

A very strong smell doesn't mean there's too much chlorine, it means just the opposite. What chloramines are and how to correct them.

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Water chemistry

Aug 28, 2026

How to raise or lower your pool's pH, step by step

The parameter that gets thrown off balance the most, and drags all the others with it. How to tell what's wrong and fix it safely.

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Water chemistry

Mar 12, 2026

Your pool's water parameters: what they mean and why they matter

What pH, chlorine, alkalinity and hardness are, what range they should be in, and what happens if they're not kept under control.

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Water chemistry

Mar 26, 2026

Chemical treatment of your pool water: complete guide

Chloramines, shock treatment, water balance and how to fix the most common problems: cloudy, green, stained.

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Water chemistry

Apr 9, 2026

Salt chlorination: soft water all summer, without the usual chlorine

Advantages of a salt chlorinator over traditional chlorine, and how we install it in your pool.

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Maintenance

Apr 23, 2026

Filter sand replacement: why and how often to do it

Sand compacts and loses effectiveness over the years. Signs it's time to change it and the benefits of doing it in time.

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Maintenance

May 14, 2026

Salt chlorinator cell: lifespan and when to replace it

What the cell is, how long it lasts, how to care for it, and the clear signs it's time to replace it.

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Safety

May 28, 2026

A safe pool for the whole family

Barriers, supervision and preparedness: the three layers of protection that prevent most accidents.

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Season

Jun 18, 2026

How to winterize your pool

What to do with the water at the end of the season: steps, common mistakes and why you shouldn't just leave it "as is."

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Season

Aug 14, 2026

How to open your pool in spring, step by step

The reverse of the season closing process: cover, water level, pump and filter, and rebalancing the water before the first swim.

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Safety

Sep 21, 2026

Fencing and safety regulations: what the law requires

RD 742/2013, the CTE and regional regulations, what's required for private and community pools.

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Water chemistry

Sep 22, 2026

Chlorine vs. salt: which to choose for your pool

An honest comparison of cost, maintenance and convenience between traditional chlorine and salt chlorination.

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Equipment

Sep 23, 2026

Pool energy savings: which measures pay off

Variable-speed pump, thermal cover and heat pump, where to start if you can only do one thing.

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Regulations

Sep 24, 2026

Insurance and liability: what it covers and who's responsible

What home and community insurance typically cover in the event of an accident, and what actually reduces the risk.

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Chemistry

Sep 22, 2026

Phosphates in your pool: what they are and why they matter

Algae's favorite food source, and almost always invisible on a basic test kit.

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Chemistry

Sep 22, 2026

CO2 and pool pH: Henry's Law explained

Why pH drifts up on its own with still water, and what aeration has to do with it.

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Chemistry

Sep 22, 2026

Pool enzymes: what they actually do

They break down oils and grease that chlorine alone doesn't handle well.

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Maintenance

Sep 22, 2026

Before you fire your pool maintenance tech

Signs that actually matter and signs that don't, before making a rushed call.

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Maintenance

Sep 22, 2026

Dirt lines at the pool's waterline: why they show up

That dark ring right at the water line has a specific cause and a fix.

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Maintenance

Sep 22, 2026

Heavy-metal stains in your pool: copper and iron

Brown, green or blackish, which color points to which metal, and how to remove it safely.

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Chemistry

Sep 22, 2026

Pool water turned green after shock treatment: why it happens

It isn't always algae, it can be a dissolved metal oxidizing all at once.

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Chemistry

Sep 22, 2026

Nitrates, nitrites and urea in your pool: the other contaminant

Sweat, urine, rain and garden fertilizer feed algae too.

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Chemistry

Sep 22, 2026

Pool disinfection without chlorine: real alternatives

Bromine, UV, ozone and active oxygen, what each one can and can't do.

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Maintenance

Sep 22, 2026

When should you drain and refill your pool?

It's almost always a last resort, but sometimes it really is the right call.

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Equipment

Sep 22, 2026

Is pool concrete actually waterproof?

Concrete and gunite are naturally porous and need a finish of their own.

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Equipment

Sep 22, 2026

Salt pools: why white calcium flakes appear

Precipitated calcium carbonate, almost always caused by high pH combined with hard water.

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