Water Balance

Chlorine problems

- problems associated with Chlorine levels are not difficult to pin down

Chlorine has been added, but there is no reading on the test kit

Possible cause 1 -

Old, inaccurate or ineffective test kit

Cure: - Buy a new kit, or test-strips, or change the batteries in your Photometric Meter every year - they are all inexpensive and accurate testing is key to understanding what is happening in your pool

Possible cause 2 -

The Chlorine level may be so high that it bleaches the colour in the test kit, or exceeds the range of a Photometric Meter (although both of these are unlikely)

To check this diagnosis see if you can smell Chlorine at the surface of the water, or repeat the test with only a droplet of pool water, diluted with tap water, in the test tube and watch closely to see if there is a discolouration before the bleaching occurs

Cure: -

Determine the level of Chlorine by diluting the sample of pool water with an equal quantity of natural or distilled water; multiply the answer by 2

If there is still no reading, dilute the water sample with 3 parts of water; then multiply the answer by 4, and so on

Alternatively you can have a sample of your pool-water tested at most pharmacies and pool-shops

If the actual Chlorine reading is under 10ppm, suspend dosing until it drops over time

If the Chlorine reading is higher than 10 ppm, reduce the free Chlorine by adding Sodium Thiosulphate

WARNING: dose Sodium Thiosulphate at 250g per 50 cubic meters

Apply in several small additions and test Chlorine levels after each dose

Overdosing with Sodium Thiosulphate could leave you with a Chlorine deficit for weeks

Chlorine level is difficult to maintain

Possible cause 1 -

The free Chlorine is being decomposed by UV from the sun’s rays

Cure: -

If you are using Sodium Hypochlorite or Calcium Hypochlorite, add Cyanuric Acid (stabilizer) at a rate of 500 grams per 50 m³ or 1 pound per 13,000 US Gallons

This should be dosed directly into the pool

Alternatively, change to a stabilized Chlorine donor such as Trichloro

2nd possibility -

High water temperature

Cure: -

Keep a close eye on Chlorine levels in hot weather

Once the water temperature goes above 26 °C, the Chlorine demand will roughly double for every 5 °C

Increase the dose rate of Chlorine proportionately as the temperature rises

3rd possibility -

A build-up of pollutants due to low Chlorine, causing an increased Chlorine demand

Cure: -

Superchlorinate to 10ppm to oxidize bather waste and to react out chloramines

4th possibility -

Incorrect level of Total Alkalinity (TA)

Cure: -

TA is a measure of the bicarbonates that are dissolved in the water

TA is important because if it’s to low you will experience ‘pH Bounce’ and if it’s too high you’ll have great difficulty in changing the pH value

Take a sample of your pool water to your local pool-shop or pharmacy (some Photometric Testers do test for TA)

They will test the water and tell you the TA level of your pool water

Increase TA by adding dissolved Sodium Bicarbonate with the pump on

Reduce TA by adding dissolved dry acid to the deepest part of the pool with the pump off

Check the container instruction for quantities

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Calcium Hardness (CH)

- is a measure of the amount of dissolved Calcium (usually as Calcium Carbonate) in your pool water

The ideal range is 250 - 350 ppm but 100 - 500 ppm is acceptable

Readings above 500 ppm (High Calcium Hardness) can cause Calcium (as Calcium Carbonate) to precipitate from the water causing cloudiness and lime-scale deposits

High Calcium Hardness also causes eye irritation

If and when the Calcium Hardness rises above 400 ppm you should replace some of the water or add a Rust and Scale Remover to prevent cloudy water

Readings below 100 ppm (Low Calcium Hardness) can cause problems similar to low Total Alkalinity and lead to corrosion of plaster, grout and metals and can cause also staining

Low Calcium Hardness level can be corrected by adding Calcium Chloride

We supply all plant and equipment featured on this website. All our work is Guaranteed; Parts and Labour

Note: - Please contact our recommended pool professionals for supply and installation of all pool-related services: -

Andalusia and the Costa del Sol - Pool Safety Spain

Nerja area - This email address is being protected from spambots. You need JavaScript enabled to view it.

*We only offer Quotations: - a fixed, agreed price that cannot, and will not, be increased. We do not give 'estimates', as an estimate offers the client no guarantee of final price

Ken Walker - MyPoolGuru©

Total Alkalinity (TA)

- AKA 'TA' - is a measure of the total alkaline substances found in the pool water

Basically, it’s a measure of the dissolved bicarbonates

It’s in the same area as pH, but is distinct from it

In swimming pool water, we measure bicarbonate alkalinity, which should be between 80 - 120ppm

When TA is within this range, it prevents rapid pH changes and "stabilizes" the pH level

If the TA is too low, the grout between the tiles, or the top surface of the pool plaster will be gradually eaten away, metals will corrode, the pool's walls and floor can stain, the water can turn green, eyes will burn and we can have pH bounce (pH rapidly going up and down, seemingly at random)

If the TA is too high, the pH is difficult to adjust, the water becomes cloudy, the Chlorine loses its effectiveness as a sanitizer and (according to your test kit) the pool constantly needs acid or pH-minus powder

It is recommended that you test the TA monthly, but in practice it changes very little in a well-maintained pool

Most Reagent Test-kits do not measure for TA, but if you take a plastic bottle of water from your pool into a pool-shop or pharmacy they will be able to test TA for you

Alternatively, use a Photometric Tester which will test the TA for you

To raise the level of TA, use Sodium Bicarbonate; it is the only chemical which will do this without increasing the pH unduly

To raise the TA of your pool by 10 ppm use 700g of Sodium Bicarbonate for every 50m³ of water

Or 20oz of Sodium Bicarbonate for every 10.000 US Gals of water

Note: - you should add Sodium Bicarbonate at this rate every 4 days until the level is correct

Raising the TA can therefore be quite a time-consuming, slow process

If you just want to raise the TA, pH-plus should not be used as it will affect pH also

Lowering the TA is also a slow process

Acid, either liquid or dry, is added to the deepest part of the pool with the pump and filter off

Add acid a little at a time, diluting or dissolving it before pouring it into the pool

Wait 3 days between applications. It could take weeks or even longer to reduce the TA if it is very high

To lower the TA of a 50 m³ pool by 10 ppm use 800ml of liquid Hydrochloric Acid at 30% concentration

Total Alkalinity remains too low

Likely cause - Bicarbonates in the pool are diluted by low-bicarbonate mains water when you top the pool up

This is common in soft water areas

Cure: - Add Sodium Bicarbonate to raise the total alkalinity to around 100ppm

A dose rate of 1.5kg per 50 m³/ 13.000 US Gals of pool water will raise the alkalinity level by 20ppm

Pre-dissolve the Sodium Bicarbonate and add to the pool via the skimmer with the pump on

Sodium Bicarbonate is the only chemical that can adjust Alkalinity upwards without affecting pH

Sodium Bicarbonate is generally cheaper at catering supply outlets than it is at a pool-shop

TA and Pool-covers

As outlined above, TA is a measure the total alkaline substances dissolved in the water, basically a measure of the dissolved solids (TDS) in the water

A pool-cover will greatly reduce evaporation, so your TA will take longer to rise and you won't need to fill the pool so often

We supply all plant and equipment featured on this website. All our work is Guaranteed; Parts and Labour

Note: - Please contact our recommended pool professionals for supply and installation of all pool-related services: -

Andalusia and the Costa del Sol - Pool Safety Spain

Nerja area - This email address is being protected from spambots. You need JavaScript enabled to view it.

*We only offer Quotations: - a fixed, agreed price that cannot, and will not, be increased. We do not give 'estimates', as an estimate offers the client no guarantee of final price

Total Dissolved Solids (TDS)

- AKA 'TDS' - is the measure of the total amount of dissolved material in the water and is measured in parts-per-million (ppm)

Soluble substances that enter a swimming pool eventually end up as dissolved solids

These substances include dissolved salts in the mains water, water treatment chemicals (such as aluminium-based flocculants), soluble pollution from bathers and disinfection by-products - i.e. those substances formed by the reaction between the pool sanitizer and bather pollution

The maximum TDS level for pools is 1,500 ppm

At values above 1500 ppm, staining may well develop

As water evaporates dissolved solids remain behind and therefore TDS level increase over time

High TDS reduces the effectiveness of pool chemicals, preventing them from doing what they're supposed to and also causes ioniser and saltwater chlorinator plates to become scaled more quickly, resulting in the need to clean them more frequently.

The water may also become turbid (cloudy) - in this case do not use an aluminium-based flocculant because it will leave behind sulphates which will add to the TDS problem (but you can use Jolly Gel )

The only practical long-term solution to high TDS is to drain some or all of the water from the pool and replace it with fresh, low TDS, water

Rain water (and the condensate from air-conditioning units) contains almost no dissolved solids so rain filling the pool, when the excess water must be removed, will help to reduce TDS

Low TDS will result in wild swings in pH, seemingly at random

A regular back-washing routine will help to control TDS and prevent it from rising too quickly

We supply all plant and equipment featured on this website. All our work is Guaranteed; Parts and Labour

Note: - Please contact our recommended pool professionals for supply and installation of all pool-related services: -

Andalusia and the Costa del Sol - Pool Safety Spain

Nerja area - This email address is being protected from spambots. You need JavaScript enabled to view it.

*We only offer Quotations: - a fixed, agreed price that cannot, and will not, be increased. We do not give 'estimates', as an estimate offers the client no guarantee of final price