Pool needs shocking

Since the storm two weeks ago our pool chemistry has been tricky.
We tried shocking with javel on Friday but now have a free chlorine of .16 and total chlorine of .6 which means we needs to shock our pool again( properly).
The pool shop said ( I think) to do it 2 days.
Is it possible to do it today all in one go as my son and grandson are arriving tomorrow and obviously they would like to use the pool so we need to allow the chlorine levels to reduce.
Any help gratefully received.

If I took all my clothes off, would that shock it sufficiently?


I think all the water would disappear.:wink:

And for some reason the alkalinity has dropped to 45. I am getting heartily fed up already of the jolly pool. I think I try too hard.

Teresa, more information on the pool please. size, construction Vinyl/plastic or tiled etc. What are your water test results including stabiliser level?

10 x 5 m roughly( about 60m3). Stabilizer 44mg/l
Total chlor .16
Combined chlorine. 44
Alkalinity 45
Ph 7.4
Vinyl pool
Phosphates 1,156mg I think because initially I was struggling with ph levels and also algae from storm although we did clear pool next day.
As I needed to do something earlier I put 380 grams of chlore shock in at 4pm and have got pool pump running.

That’s 0.16 and 0.44

The chlore tub recommended 4x80grams for 50m3 pool.

The pool actually looks really good,strangely. I’ve brushed it a lot.
Do I have chlorine lock?

Chlorine lock does not exist, it’s the product of pool people not knowing what they are talking about. Likewise shock, it’s a process not a product. The greatest danger for you is using choc products you are adding to your stabiliser lever (CYA 44) you don’t really want to take it much higher so should switch to Eau de javel from a brico shed at around 12-15 euros for 20 litres 600ml will give you about 1ppm of chlorine so add 1.8 liters of javel and hold that level, perfectly safe to swim in without going to shock whilst children are with you. With your stabiliser at 44 you should be running your chlorine level at 2.2-3.3ppm especially with your 1,156mg/l phosphates (that should be 0 ideally).
Get some phosphate remover for later, it may cloud your water for a while so use when the pool is not in use for a few days.
Do not adjust your alkalinity! the figures stated are for concrete/plaster/tiled pools, it’s not needed in vinyl or plastic pools. Your pH will then stay very stable, I run mine about 37-40ppm and haven’t used any pH minus.

No problem with what you have done but shocking a pool is just raising the chlorine level to a point where all chloramines are burnt out of the pool and that level can often be held for several days as required to achieve this, your combined chlorine is not too bad and using 3ppm of chlorine will achieve the same thing over a week or so without going to shock level.
Hope that helps but happy to answer any questions.

Thank you so much. I realised later that I probably panicked slightly as my grandson is coming. Will go back to the javel. The pool looks fine this morning. I will test it when I return from French class. The only thing I find is every time I use javel my ph seems to climb. Not sure why. The phosphates may be a combination of the storm and ph minus. Will get some phosphate remover.
Thanks again.

The pH climbs a little due to the remenents of sodium hydroxide which help stabilise the chlorine a bit and left over from the production.
Having a lower alkalinity and some CYA stabiliser will help keep the pH in the conventional range.

That said, when CYA stabiliser is present in the water the pH does not matter provided it is higher than pH7. Below that there is eye irritation. The effect on the sanitiser of a pH of 7 to 9 is so minimal it is not worth worrying over. Your water will reach its own happy pH, generally about 8 ish.

The above CYA fact is only applicable when CYA stabiliser is present. If it’s an indoor pool without stabiliser then the chlorine has a bigger sanitising effect with the lower pH.


Thank you.

Hi John
You recommended I use some phosphate remover. I am struggling to find any. Do you know what I should look for please. My local pool shop seem strangely reluctant to acknowledge I need it although my phosphates are over 1000. I had to shock my pool Saturday and I know that the algae problem is more likely to reoccur if I don’t do something about the phosphates.
I live in Perigord vert.
Many thanks

Also since shocking my pool my combined chlorine is 2.5 and my fc is 1.36. I know these will both drop and the combined chlorine was caused by a bad algae problem ( due probably to phosphates). The pool shop seem more concerned to increase my alkalinity ( it’s 50) rather than decrease my phosphates.
What reading should my cc be for it to be safe to swim once my fc has dropped to 5 or less.
If it remains high should I use sodium thiosulphate?
Ph is 7.4
Many thanks.

Hi Teresa,
There is from memory a Cash Piscine in the Perigord vert? They sell Antiphosphate 29.90 euros.
Yes I am sorry to say there are a lot of French and English pool shops who do not know what they are doing.

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Thank you. I will search it out.
I realise now that the phosphates probably came from the field at harvest.
I should have probably acted more quickly. I’ve learned the hard way that prevention is so much better than cure.
If my chloramines remain high I’m not sure quite what to do.

Hi Teresa, if I may, you are low on your free chlorine which maybe why your not really done shocking yet. Forget the idiots at the pool shop! With a vinyl pool your alkalinity is fine, all the published figures relating to the alkalinity levels are for plaster and tiled pools. If you go much higher with your alkalinity the off gassing of CO2 due to saturation will cause the pH to rise, meaning of course a visit to the pool shop for acid or pH minus and so the cycle goes on.
If you decrease your phosphates you won’t be buying more chlorine, algaecide, winteriser etc.

With your CYA stabiliser at 44 (assuming it hasn’t changed much) your min free chlorine should be 2.2-3.5ppm to maintain a proper residual of sanitiser. This level is not high and neither is 5ppm when the CYA is 44ppm. To illustrate the idea, a commercial indoor pool (no CYA) will be running at 3ppm or thereabouts which would be around 10X higher in sanitiser than your pool, because of the CYA bound to the chlorine reducing the hypochlorous acid. It’s tricky to use sodium thiosulphate with an already low chlorine level, best avoid.

I realise now that the phosphates probably came from the field at harvest.
And bird poop which is around 90% phosphate

Sorry I may have confused you with tagging onto an old post. My free chlorine yesterday was 1.36 and my combined was 2.5. My ph was 7.4.
I’m worried about such high cc as I obviously did a big shock on Saturday for the algae.
If I keep my free chlorine at 4ppm but the chloramines are raised can we still swim as I am not sure?
Many thanks