Introduction
Keeping pool water clean and safe requires the use of various chemicals, each with a specific function. Understanding what each product does, when to use it and how to dose correctly is fundamental for effective and economical maintenance.
In Margem Sul, where we face specific challenges such as well water with high hardness, maritime influence and intense sun exposure, knowing the available pool chemicals well helps choose the most suitable solutions for each situation.
This complete guide presents all the essential pool chemicals, from disinfectants to special products, with clear instructions for use, dosages and safety precautions.
Product Categories
Overview
| Category | Main Function | Frequency of Use |
|---|---|---|
| Disinfectants | Kill microorganisms | Continuous |
| pH regulators | Balance acidity | As needed |
| Alkalinity regulators | Stabilise pH | As needed |
| Algicides | Prevent/eliminate algae | Weekly/treatment |
| Flocculants/clarifiers | Improve clarity | As needed |
| Special products | Specific problems | Occasional |
Disinfectants
Types of Chlorine
| Type | Form | CYA | Best For |
|---|---|---|---|
| Calcium hypochlorite | Granules/tablets | No | Shock treatments |
| Dichloroisocyanurate (dichlor) | Granules | Yes | Quick chlorination |
| Trichloroisocyanurate (trichlor) | Tablets | Yes | Continuous chlorination |
| Sodium hypochlorite | Liquid | No | Automatic dosing |
Stabilised vs Unstabilised Chlorine
| Characteristic | Stabilised | Unstabilised |
|---|---|---|
| Contains CYA | Yes | No |
| UV protection | Yes | No |
| Accumulation | Can accumulate CYA | No accumulation |
| Ideal use | Daily maintenance | Shocks, indoor pools |
| Cost | Lower medium-term | Higher (more consumption) |
Chlorine Dosage
For maintenance (1-3 ppm):
| Pool Volume | 200g Tablet | Granules/day |
|---|---|---|
| 20 m³ | 1 tablet/week | 20-40g |
| 40 m³ | 2 tablets/week | 40-80g |
| 60 m³ | 3 tablets/week | 60-120g |
| 80 m³ | 4 tablets/week | 80-160g |
For shock (10+ ppm):
| Volume | Calcium hypochlorite 65% |
|---|---|
| 20 m³ | 300-400g |
| 40 m³ | 600-800g |
| 60 m³ | 900-1200g |
| 80 m³ | 1200-1600g |
💡 Dica Profissional
In Margem Sul, with intense sun during summer, unstabilised chlorine can lose 90% of its effectiveness in just a few hours. Always use stabilised chlorine for daily maintenance, reserving unstabilised for shock treatments.
Bromine
Characteristics:
- Effective at high temperatures
- Less irritating than chlorine
- Doesn't produce strong smell
- More expensive than chlorine
Ideal for:
- Spas and jacuzzis
- Heated indoor pools
- Users sensitive to chlorine
| Parameter | Ideal Value |
|---|---|
| Free bromine | 3-5 ppm |
| pH | 7.2-7.8 |
Active Oxygen (Hydrogen Peroxide)
Characteristics:
- Chlorine-free
- No smell
- Gentle on skin and eyes
- Requires more maintenance
Dosage:
- Maintenance: 50-100 ml/m³ per week
- Shock: 200-300 ml/m³
pH Regulators
pH Minus (Reducer)
Typical composition:
- Sodium bisulphate (solid)
- Hydrochloric acid (liquid)
- Sulphuric acid (liquid)
When to use:
- pH above 7.6
Approximate dosage (pH from 7.8 to 7.4):
| Volume | Sodium bisulphate | Hydrochloric acid 33% |
|---|---|---|
| 20 m³ | 200-300g | 150-200 ml |
| 40 m³ | 400-600g | 300-400 ml |
| 60 m³ | 600-900g | 450-600 ml |
| 80 m³ | 800-1200g | 600-800 ml |
pH Plus (Increaser)
Typical composition:
- Sodium carbonate (soda ash)
When to use:
- pH below 7.2
Approximate dosage (pH from 7.0 to 7.4):
| Volume | Sodium carbonate |
|---|---|
| 20 m³ | 150-200g |
| 40 m³ | 300-400g |
| 60 m³ | 450-600g |
| 80 m³ | 600-800g |
💡 Dica Profissional
Never add more than 300g of pH regulator per 10 m³ at once. Wait at least 4 hours with filtration running before testing again and making further adjustments.
Alkalinity Regulators
Alkalinity Increaser
Composition:
- Sodium bicarbonate
When to use:
- Alkalinity below 80 ppm
- Unstable pH (rises and falls easily)
Dosage (to increase 10 ppm):
| Volume | Sodium bicarbonate |
|---|---|
| 20 m³ | 300g |
| 40 m³ | 600g |
| 60 m³ | 900g |
| 80 m³ | 1200g |
Alkalinity Reducer
Method:
- Use hydrochloric acid or sodium bisulphate
- Add in small doses over several days
- Reducing pH also reduces alkalinity
Stabiliser (Cyanuric Acid)
Function
Protects chlorine from UV degradation, extending its effectiveness.
Dosage
To achieve 30-40 ppm:
| Volume | Cyanuric acid |
|---|---|
| 20 m³ | 600-800g |
| 40 m³ | 1200-1600g |
| 60 m³ | 1800-2400g |
| 80 m³ | 2400-3200g |
Precautions
| CYA Level | Situation | Action |
|---|---|---|
| 0-20 ppm | Very low | Add stabiliser |
| 30-50 ppm | Ideal | Maintain |
| 50-80 ppm | High | Don't add more |
| > 80 ppm | Problematic | Dilute water |
| > 100 ppm | Chlorine lock | Partial draining |
💡 Dica Profissional
Stabiliser doesn't degrade and only leaves the pool with the water. In pools that have used stabilised chlorine for years, CYA can accumulate excessively. In Margem Sul, we recommend renewing 20-30% of the water annually.
Algicides
Types of Algicides
| Type | Action | Concentration | Use |
|---|---|---|---|
| Quaternary (quat) | Preventive | 5-10% | Weekly maintenance |
| Polymeric (polyquat) | Preventive | 30-60% | Maintenance, no foam |
| Copper | Curative | Variable | Algae treatment |
| Copper sulphate | Curative | 100% | Black algae |
Dosage
Weekly maintenance:
| Volume | Quaternary algicide | Polymeric algicide |
|---|---|---|
| 20 m³ | 100-200 ml | 50-100 ml |
| 40 m³ | 200-400 ml | 100-200 ml |
| 60 m³ | 300-600 ml | 150-300 ml |
| 80 m³ | 400-800 ml | 200-400 ml |
Curative treatment (visible algae):
- Triple the maintenance dose
- Combine with shock treatment
Precautions with Copper Algicides
| Aspect | Caution |
|---|---|
| pH | Maintain 7.2-7.6 (prevents precipitation) |
| Stains | May stain light finishes |
| Dosage | Don't exceed recommendation |
| Hair | May tint light hair green |
Flocculants and Clarifiers
Difference
| Characteristic | Flocculant | Clarifier |
|---|---|---|
| Mechanism | Clumps large particles | Clumps small particles |
| Result | Settles to bottom | Improves filtration |
| After use | Vacuum residue | Clean filter |
| Speed | Fast (6-12h) | Gradual (24-48h) |
Flocculant
When to use:
- Very cloudy water
- After algae treatment
- Fine particles in suspension
Procedure:
- Adjust pH to 7.2-7.6
- Turn off pump
- Add diluted flocculant
- Wait 8-12 hours
- Vacuum to waste (not to filter)
- Turn on filtration
Dosage:
| Volume | Liquid flocculant |
|---|---|
| 20 m³ | 200-400 ml |
| 40 m³ | 400-800 ml |
| 60 m³ | 600-1200 ml |
| 80 m³ | 800-1600 ml |
Clarifier
When to use:
- Slightly cloudy water
- Preventive maintenance
- Improve filter efficiency
Weekly dosage:
| Volume | Clarifier |
|---|---|
| 20 m³ | 50-100 ml |
| 40 m³ | 100-200 ml |
| 60 m³ | 150-300 ml |
| 80 m³ | 200-400 ml |
Calcium Hardness Regulator
Calcium Increaser
Composition:
- Calcium chloride
When to use:
- Hardness below 200 ppm
- Liner or vinyl finish
Dosage (to increase 10 ppm):
| Volume | Calcium chloride |
|---|---|
| 20 m³ | 200g |
| 40 m³ | 400g |
| 60 m³ | 600g |
| 80 m³ | 800g |
Anti-Scale (Sequestrant)
When to use:
- Hardness above 400 ppm
- Well water
- Scale deposits
Dosage:
| Use | Quantity |
|---|---|
| Initial | 500 ml/50 m³ |
| Weekly maintenance | 100 ml/50 m³ |
💡 Dica Profissional
In Margem Sul, especially in Palmela, Moita and Azeitão, well water frequently has hardness above 400 ppm. Preventive use of anti-scale is essential to avoid deposits on equipment and surfaces.
Special Products
Metal Sequestrant
Function:
- Prevents iron and copper stains
- Keeps metals in solution
When to use:
- Well water
- After metal stains
- Preventively
Dosage:
- Initial: 500 ml/50 m³
- Maintenance: 100 ml/50 m³ fortnightly
Stain Remover
| Stain Type | Product | Dosage |
|---|---|---|
| Organic (leaves) | Chlorine + brushing | Shock + brush |
| Metallic (iron) | Ascorbic acid | 100g/10 m³ |
| Scale | Hydrochloric acid | Localised application |
| Black algae | Copper sulphate + chlorine | Combined treatment |
Tile Cleaner (Descaler)
Function:
- Removes deposits at waterline
- Eliminates oils and grease
Use:
- Apply with sponge
- Scrub gently
- Rinse well
- Frequency: fortnightly
Antifoam
When to use:
- Persistent foam on surface
- After excessive quaternary algicide use
- Cleaning products in water
Dosage:
- 50-100 ml per 50 m³
Storage and Safety
Storage Rules
| Rule | Reason |
|---|---|
| Cool, dry place | Prevents degradation |
| Away from sun | Some products degrade |
| Separate oxidisers from acids | Avoids dangerous reactions |
| Original containers | Identification and safety |
| Out of children's reach | Safety |
| Ventilated area | Prevents vapour buildup |
Incompatibilities
| NEVER Mix | Result |
|---|---|
| Chlorine + acid | Chlorine gas (toxic) |
| Chlorine + ammonia | Chloramines (toxic) |
| Different oxidisers | Violent reaction |
| Concentrated acid + base | Exothermic reaction |
Protective Equipment
| Product | Minimum PPE |
|---|---|
| Chlorine granules/tablets | Gloves, goggles |
| Acids | Gloves, goggles, apron |
| Liquid products | Gloves |
| All | Don't inhale vapours |
How to Add Products
General Rules
- Always dilute solid products in bucket with water before adding
- Add around the perimeter, not at one point
- With filtration running (except flocculant)
- Wait between different products (minimum 30 minutes)
- Don't swim for 30-60 minutes after adding
Order of Addition
If you need to add several products:
- Adjust alkalinity (wait 4h)
- Adjust pH (wait 4h)
- Add stabiliser if needed (wait 24h)
- Add chlorine or disinfectant
- Algicide (after chlorine normalises)
- Clarifier (last)
Dosage Calculations
Basic Formula
Quantity = (Pool volume × Dosage per m³) / Product concentration
Practical Example
Problem: Raise chlorine from 0.5 ppm to 2 ppm in a 50 m³ pool Increase needed: 1.5 ppm Product: Dichlor 56%
Quantity = (50 m³ × 1.5g) / 0.56 = 134g of dichlor
Quick Conversion Table
| To increase | 56% granular chlorine per 10 m³ |
|---|---|
| 1 ppm | 18g |
| 2 ppm | 36g |
| 5 ppm (shock) | 90g |
| 10 ppm (strong shock) | 180g |
Frequently Asked Questions
Can I mix products from different brands?
Yes, as long as they are the same type (e.g., two quaternary algicides). Never mix different categories in the same container. Add each product separately to the pool.
What's the shelf life of pool chemicals?
Most maintain effectiveness for 2-3 years if stored correctly. Granular chlorine may lose potency after 1 year opened. Always check packaging for specific dates.
Why does chlorine disappear so quickly?
Common causes: lack of stabiliser (CYA), excess organic matter, high temperature, intense sun, or incorrect pH. In Margem Sul, strong summer sun is often the culprit if CYA is low.
Is it better to use tablets or granular chlorine?
Tablets are more convenient for continuous chlorination (in floater or skimmer). Granules are better for quick adjustments and shock treatments. Most owners use both.
How long should I wait to swim after adding chemicals?
Depends on the product. General rule: 30-60 minutes for normal adjustments. After shock, wait until chlorine drops below 3 ppm (test before swimming).
Conclusion
Correct use of pool chemicals is essential for keeping water clean, safe and pleasant. The main points are:
- Know each product and its specific function
- Follow recommended dosages - more is not better
- Respect the order of addition when using multiple products
- Store correctly and never mix incompatible products
- Use protection when handling chemicals
- Test regularly to confirm results
In Margem Sul, with the particularities of local water, it's especially important to use anti-scale and metal sequestrant preventively, in addition to maintaining adequate stabiliser levels.
If you need professional help with the chemical treatment of your pool in Margem Sul, ManutençãoPiscinas is here to help. Contact us for a no-obligation quote.
