PH 9.8 spike after adding new pool cover for winter

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
GLO
I'm new here
I'm new here
Posts: 7
Joined: Sat 04 Jul, 2020 02:08
My Pool: Concrete Pool: 33,000L
Beadcrete
Astral Equilibrium 25 Salt Water Chlorinator (with PH and ORP Sensor)
Astral P320XT variable speed pump
Astral Filter with glass media

PH 9.8 spike after adding new pool cover for winter

Postby GLO » Sat 04 Jul, 2020 02:17

Hi,

Im new here so please be nice, and i'm hoping to learn as much as i can for our new concrete pool installed in Feb this year.

All my equipment is Astral and im using the AI in the Equilibrium 25 which has PH and ORP probes.
All has been running well and its winter here in Australia at the moment.

I installed a new bubble pool cover for winter and since installing it, i noticed a PH spike and its sitting at 9.8 now.

Last week I had the water tested and it was 8.4 according to the local pool shop. and Astral customer support said to calibrate my sensor to 8.4 given the pool reading.

Nothing changed and I had Astral come out and they installed new probes and salt chlorinator. However the new probes read 9.8 straight away.

I set the Astral Equilibrium 25 to manually does 400ml or acid but that has made no difference.

Im planning on adding 400ml of muriatic acid to the pool to shock it tomorrow morning, but am stumped as to why the PH would jump after installing the bubble pool cover.

All help is appreciated and thanks in advance.


Denniswiseman
Pool Industry Leader
Pool Industry Leader
Posts: 1828
Joined: Tue 06 Sep, 2011 05:48
My Pool: 10k inground fibreglass, Telescopic Cover, Hayward Powerline pump, Quality filter with glass media, 27kw output heat pump, K-2006C test kit
Location: United Kingdom

Re: PH 9.8 spike after adding new pool cover for winter

Postby Denniswiseman » Sat 04 Jul, 2020 13:50

Aeration would raise pH but covering it would do the opposite
Do you have any aeration causing features, waterfall, infinity edge
What is your TA as TA and pH work together
Keep lowering the pH and see where the TA ends up
You really need to get yourself a decent FAS/DPD test kit to get accurate results
GLO
I'm new here
I'm new here
Posts: 7
Joined: Sat 04 Jul, 2020 02:08
My Pool: Concrete Pool: 33,000L
Beadcrete
Astral Equilibrium 25 Salt Water Chlorinator (with PH and ORP Sensor)
Astral P320XT variable speed pump
Astral Filter with glass media

Re: PH 9.8 spike after adding new pool cover for winter

Postby GLO » Sat 04 Jul, 2020 17:02

Thanks for your reply.

I have no waterfall or infinity edge.

Total alkalinity is 40. I know it needs to be somewhere between 80 and 120.
Denniswiseman
Pool Industry Leader
Pool Industry Leader
Posts: 1828
Joined: Tue 06 Sep, 2011 05:48
My Pool: 10k inground fibreglass, Telescopic Cover, Hayward Powerline pump, Quality filter with glass media, 27kw output heat pump, K-2006C test kit
Location: United Kingdom

Re: PH 9.8 spike after adding new pool cover for winter

Postby Denniswiseman » Sun 05 Jul, 2020 16:57

GLO wrote:Thanks for your reply.

I have no waterfall or infinity edge.

Total alkalinity is 40. I know it needs to be somewhere between 80 and 120.

Not necessary as a lower TA helps keep pH stable
Keep reducing pH with acid and add bicarbonate of soda to raise TA
Use Pool Maths towork out how much to add
GLO
I'm new here
I'm new here
Posts: 7
Joined: Sat 04 Jul, 2020 02:08
My Pool: Concrete Pool: 33,000L
Beadcrete
Astral Equilibrium 25 Salt Water Chlorinator (with PH and ORP Sensor)
Astral P320XT variable speed pump
Astral Filter with glass media

Re: PH 9.8 spike after adding new pool cover for winter

Postby GLO » Sun 05 Jul, 2020 18:20

Thanks.

My local pool shop said to add 4kg of BiCarb which I did 20hrs ago.

PH has dropped from 9.8 to 9 right now.
They also suggested to put another 500ml of Muriatic Acid in. Which I am about to do now.
GLO
I'm new here
I'm new here
Posts: 7
Joined: Sat 04 Jul, 2020 02:08
My Pool: Concrete Pool: 33,000L
Beadcrete
Astral Equilibrium 25 Salt Water Chlorinator (with PH and ORP Sensor)
Astral P320XT variable speed pump
Astral Filter with glass media

Re: PH 9.8 spike after adding new pool cover for winter

Postby GLO » Fri 10 Jul, 2020 06:06

PH now sitting at 8.6 after the 2nd 400ml of muriatic acid.

I feel like it needs another 400ml to get it down into the 7s. Thoughts?
Denniswiseman
Pool Industry Leader
Pool Industry Leader
Posts: 1828
Joined: Tue 06 Sep, 2011 05:48
My Pool: 10k inground fibreglass, Telescopic Cover, Hayward Powerline pump, Quality filter with glass media, 27kw output heat pump, K-2006C test kit
Location: United Kingdom

Re: PH 9.8 spike after adding new pool cover for winter

Postby Denniswiseman » Fri 10 Jul, 2020 10:14

Use Pool Maths to work out just what you need
It's simple to use but what you don't understand come back and we'll sort it
GLO
I'm new here
I'm new here
Posts: 7
Joined: Sat 04 Jul, 2020 02:08
My Pool: Concrete Pool: 33,000L
Beadcrete
Astral Equilibrium 25 Salt Water Chlorinator (with PH and ORP Sensor)
Astral P320XT variable speed pump
Astral Filter with glass media

Re: PH 9.8 spike after adding new pool cover for winter

Postby GLO » Wed 22 Jul, 2020 16:18

Thanks Denniswiseman,

I missed your reply and will check that out.

After my last post I, adding 4kg bi carb and next day another 400ml acid, it dropped to 8.6 and my local pool shop asked to wait 2-3 weeks to stabilise.

I visited them again with a fresh sample, noting my Astral equilibirum was reading 8.8 with chlorine levels high.

The pool shop test reported 8.4 (not sure if I need to recalibrate sensors again) and suggested to add 350ml acid and leave the pool cover off for a few weeks for the sun to deplete some chlorine, and add another bag of salt. (I don't understand how adding more salt will help).


After adding the acid a few days back this mornings ph reading is 8.3.(this may be 7.9 based on the reading delta from last week)

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