Have a cloudy pool after shocking 3 times!

[TonyN]

Hi all

I am new to this site and have been learning about pools for around 18 months. We moved to South West France in 2014 from the UK, to start a new adventure! We have started a Property Management company, which unexpectedly has resulted in looking after a few pools too........so I think I've got to grips with the chemistry thing, and reading the Pool School kind of confirms that I have a basic understanding. So on to the problem.....

The pool is 80m3 and has just had a new pump fitted, but I 'think' the sand in the filter is quite old (the current owner bought the house 3 years ago and doesn't know how old the sand is)......since opening in June, I cannot get a chlorine reading, its zero. The total chlorine is reading 0.5, Alkalinity 120, pH 7, TH 200, CYA 40. Over a period of 14 days, I've shocked the pool 3 times.

Today the pool is cloudy, similar to the state if the Alkalinity & PH are too high, kind of almost milky (it was very green). After maybe 2 or 3 hours, the water flow slows to a trickle from the returns and the pressure gauge rises from the bottom of the 'green' to the top, so within the green range (sorry, didn't look at psi).

So I'm thinking, do I need to keep shocking until I can get the chlorine reading up to 2 or 3?? Or does it sound like a filtration problem? But would the filtration problem effect the chlorine reading??

I hope you guys can help me, the local pool guy says after he fitted the pump, that he has no more time!

Best

Tony

 

[JohnT]

Welcome to TFP!

When water is very dirty, it can consume all the chlorine in a "shock" in less than an hour. We prefer the SLAM Process which means Shock Level and Maintain, meaning you raise chlorine to shock level and then keep adding as needed (which can be hourly) until the heavy consumption drops.

I doubt you have a filter issue. The fact that it is clogging tells you it is working. If it continues to do so after the chemistry is straightened out, there may be an issue.

 

[TonyN]

Ok, so I'm off to buy more shock. Other than low CYA, is there any other reason I'd have a zero reading on FC? It just seems odd after shocking 3 times that the reading is still zero......? I'll report back after the next round of shocking, testing hourly this time and not the following day......

 

[JohnT]

Ok, so I'm off to buy more shock. Other than low CYA, is there any other reason I'd have a zero reading on FC? It just seems odd after shocking 3 times that the reading is still zero......? I'll report back after the next round of shocking, testing hourly this time and not the following day......

If it's been more than an hour since you added anything, it's not at all surprising you have zero. Chlorine can be consumed extremely fast, especially the first few times you add it. Be careful what kind of shock you are using. They all add something besides chlorine, and often it's something you don't want. If you are using cal-hypo, it could be contributing to the cloudiness by adding calcium. Liquid chlorine or plain laundry bleach is the least likely to cause other issues.

 

[TonyN]

Thanks JohnT.........The chlorine available here is the trichloroisocyanuric acid, and you are dead right, its lifting the cyanuric acid. So having done two shocks within 2 hours, the pool is definitely starting to clear, but still no chlorine reading.

I've bought the closest thing to the 6% bleach I could find here, which is 2.6%, but I've used the pool maths calculator here and put more of it in.......so I'm anxious to see the results tomorrow! The renter is going to shock again this morning and is sweeping.

What hasn't helped is both skimmer baskets are broken, so I've had to put skimmer socks on to stop the pump strainer clogging, which was slowing the already slow filtration. I'm going to change the sand in the filter although I've not done it before......the filter says 150kg of 0.5 - 0.7mm sand, but we only have 0.5 - 1.5mm available in the shops here, do you think this will be ok?? I can imagine a size too small could a problem, maybe finding its way back to the pool, but some oversized sand I'm not sure......

 

[JohnT]

If you don't have a chlorine reading, you need to add more right away.

 

[TonyN]

Update - Pool finally clear! And I have a chlorine reading and good balance on the other stuff........After all the shocking that wouldn't lift the chlorine reading and only increasing the Cya to around 150ppm, I decided to empty at least a third of the water in the pool and change the sand in the sand filter, really starting from scratch.

Now I have a decent flow from the returns (not good, just decent), and having shocked the pool I now have a chlorine reading and good chemical balance.

Thanks for the help guys.