Water Problems

brown water from tap

- when you think about it, keeping fifty tons or more of exposed-to-the-elements water in crystal clear condition is no easy task

Any pool is constantly under assault from algae and fungi spores, garden debris, rain, sun, wildlife, pets, building/quarry/road dust and a host of other pollutants

That's before any humans get into the water and add their share of sun-oils, hair, dead skin, mucus, body fats, sweat, faecal matter and urine - (yes, I'm afraid people still do), never mind the effect the Labrador and the local wildlife can have on your pristine pool

When pools go bad they can do it very quickly. After a summer storm your pool can take on the appearance of a murky, green swamp overnight. Not a pretty sight in the morning and an expensive mess to sort out

The pool-owner is left to clean the mess up, or leave it to his pool cleaner and, at the end of it all, pay the bill or -  you could learn how to clean and maintain your pool by following the advice on this site . . . 

Unfortunately, accurate diagnosis of pool water problems is not always straightforward. It’s often a case of considering the possibilities and identifying the most likely cause from other evidence; e.g., Test kit results and/or the appearance of the water, the pool surfaces and other factors

Read the possible causes for each symptom and pick the most likely suspect - if that doesn’t solve the problem; try the next most likely

Cloudy/Milky Water

There are four possibilities - your test kit will help you to decide which the culprit is

1st possibility - suspended particles give a milky white discolouration

This is likely to be caused by precipitation of dissolved minerals as a result of high pH

Cure: - Reduce the pH

To lower pH by 0.2 add Hydrochloric Acid at a rate of 1 litre per 50 m³ (13,000 US Gallons) of pool water

Run the pump for 4 hours after dosing then test again

Repeat until correct reading is reached

2nd possibility - dirt or bather pollution build up due to low chlorine or poor filtration

Cure: - clean the filter, Superchlorinate to 10ppm and then apply a Flocculant

3rd possibility - the levels of stabiliser (Cyanuric Acid) are too high. The Chlorine takes longer to kill organisms, which can then proliferate and lead to haziness in the water

Cure: - Replace some of the pool water by draining to waste (or carry out an extra-long backwash), top up with fresh water, then Superchlorinate to 10ppm

4th possibility - ineffective filtration

Cure: - Check the filter media and replace if necessary

Change the filter contents every 4 years (every 7 years if using Zeolite)

Cloudy, green  water

Cause - low chlorine levels or ineffective chlorine have allowed green algae to flourish

Cure: - Superchlorinate to 10ppm (25ppm for more serious problems) and leave the pump running for 24 hours to kill the algae

Brush all surfaces to dislodge algae and to improve the circulation of the superchlorinated water

Clean the filter after 24 hours

Any water haze can be removed with flocculant or Jolly Gel

If your pool is susceptible to algae use an algaecide monthly

Rust-stained Water

Caused by: - The corrosion of ferrous parts of the circulation system by low pH water

Cure: - Act swiftly to prevent further damage - such as staining of the plaster, grout or liner

Check with your Pool Shop to see if it is safe to empty the pool and replace the water all in one go, or if should be done by progressive dilution

Remove rust stains from the pool surfaces with a proprietary tile or liner cleaner

Use PVC fittings to replace the ferrous metal fittings

Balance the fresh water as you refill your pool

Chlorine Level Problems

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

Possible cause 1 -

Old, inaccurate or ineffective Test kit. Remember to buy a new kit every year - they are inexpensive and are your 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 approximate 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 a period of time

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

WARNING:  dose with Sodium Thiosulphate at 250g per 50m³ (13,000 US Gallons)

Apply in several small additions; wait 4 hours with the pump running 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

1st possibility - The free Chlorine is being decomposed by UV from the sun’s rays

Cure: - If you are using Sodium Hypochlorite or Calcium Hypochlorite, add stabilizer (Cyanuric acid) at a rate of 500 grams per 50m³ (13,000 US Gallons) - his should be dosed directly into the pool at the jets with the pump running

Alternatively, change to a stabilised Chlorine such as Trichlor 

2nd possibility - High water temperature

Cure: - Increase the dose rate of Chlorine proportionately as the temperature rises

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

3rd possibility - A build-up of pollutants due to low Chlorine, causing an increased Chlorine demand

Cure: - Superchlorinate to 10ppm

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 get ‘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

They will test the water, for a reasonable fee, and tell you the TA level of your pool water and any other information you need

Increase TA by adding dissolved Sodium Bicarbonate with the pump on

Reduce TA by adding pre-dissolved dry acid or Hydrochloric (Muriatic) Acid to the deepest part of the pool with the pump off

Check the container instruction for quantities

pH Problems

pH remains too low

Likely cause - This is usually due either to low pH of mains water (soft water areas), incorrect TA levels or to the use of low pH (acidic) Chlorine donors

Cure: -adjust TA as required

Correct the pH by adding pH-Plus powder

You might also consider changing to a high pH Chlorine donor to help to counteract the low pH of the fill-water

Dichlor is roughly pH neutral; Tricloro is low pH (acidic), while Calcium Hypochlorite and Sodium Hypochlorite are both high pH (alkaline) Chlorine donors

pH is permanently too high

Likely causes: -

(1) High pH of mains water (hard water areas) or

(2) Regular use of alkaline Chlorine donors such as Calcium Hypochlorite or Sodium Hypochlorite, or

(3) Hardness salts being leached from new concrete or mosaic pools

Cure: - in all of the above cases the solution is the same; correct the pH

For (1) and (2), consider a change to a low pH Chlorine source such as Trichlor to help achieve a balance between the high pH of the water and the low pH of the Chlorine donor

As for (3) - the difficulties with new pools will eventually clear up on their own accord over time

pH values are erratic and fluctuate

Likely cause - The Total Alkalinity is too low to buffer the pH

Cure: - Add Sodium Bicarbonate to raise Total Alkalinity to 80-120 ppm

Dose at 1.5kg per 50m³ (13,000 US Gallons) of pool water; pre-dissolve and distribute around the pool with the pump on

pH is locked

Likely cause - The water is over buffered due to high Total Alkalinity (TA) - this is a common problem in hard water areas

Cure: - Add dry acid (Sodium Bisulphate) to lower the TA to 80-120 ppm

The dose rate is 1kg per 50m³ of pool water or 13,000 US Gals

Add the acid, a little at a time and pre-dissolved at a dilution of 10:1, to the deepest part of the pool with the pump turned off

Leave the pump off for 24 hours, then run the pump for 4 hours, re-test and repeat as required

Note: It may take weeks of patient treatment to reduce TA to acceptable levels


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Ken Walker - MyPoolGuru©