Alkaline and PH very low, CYA high.

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
ritchie-t
Pool Enthusiast
Pool Enthusiast
Posts: 12
Joined: Mon 08 Aug, 2022 10:35
My Pool: 10X5 metre pool, sand filter.

Alkaline and PH very low, CYA high.

Postby ritchie-t » Mon 08 Aug, 2022 11:26

Hi there,

I recently bought a house with a pool and I feel I may have inherited a badly maintained pool.

The pool size is 10x5 meters, around 75 square meters volume and it uses a sand filter.

I am testing with strips, which from reading on here do not seem to be well loved. However the readings are so far away from where they should be in some cases that I don't think ultimate precision is key at this stage :lol:

Alkaline is at 0 according to the strip
The PH strip colour is actually off the chart (which goes as low as 6.2, so it must be lower than that). I can take picture if needed.
CYA is 125
Total Chlorine is 0
Free chlorine 1/2.0
Total hardness 250

Initially the free chlorine was at 0, not even changing colour on the strip. I have managed to get this acceptable after shocking the pool.
However one of the things I have not been able to sort out is the low Alkaline and PH levels.

After 4KGs of Alkaline+ nothing has changed on the test strip. I am aware now that baking soda is a cheaper alternative, but I feel that perhaps this water is too far gone and I could be chasing my tail spending vast amounts of money trying to correct it? I assume the low PH is related to the low Alkaline and fixing one would hopefully fix the other?

The CYA level you can see is very high. This going hand in hand with the low Alkaline level.

Is it worth considering a partial drain and refill? Obviously it is a big pool, so I am trying to avoid having to to do that. Keen to hear other peoples thoughts.

Many thanks.


Teapot1
Pool Industry Leader
Pool Industry Leader
Posts: 1174
Joined: Thu 29 Apr, 2021 00:43
My Pool: 12000 gallons vinyl liner,

Re: Alkaline and PH very low, CYA high.

Postby Teapot1 » Mon 08 Aug, 2022 13:07

Useless test stips, get a proper test done/buy you own proper test kit before you waste more money on chems you dont need or mess things up completely.
I may not give you the answer you want to hear, but I will give an honest opinion of your situation as you decribe it.
Denniswiseman
Pool Industry Leader
Pool Industry Leader
Posts: 2592
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: Alkaline and PH very low, CYA high.

Postby Denniswiseman » Mon 08 Aug, 2022 13:28

I agree with Teapot1
Forget about everything except the CYA
You will need to drain at least half probably 2/3 your water and replace to get your CYA down to a managaeble level before trying to change your numbers (that's if your CYA number is correct)

Excessive CYA renders your chlorine ineffective and you have to use more to get the same sanitation
For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm
To reduce your CYA you have to do a partial drain and refill
Continuous use of Trichlor/Dichlor will raise your CYA which means you have to raise your chlorine level as well

Use these common products to balance your pool
Liquid chlorine (sodium hypochlorite or plain bleach) Liquid chlorine only adds salt
Muriatic acid (hydrochloric acid) to lower pH and TA
Bicarbonate of soda to raise TA
Aeration will raise pH only
Soda ash will raise pH and TA

Test strips are commonly called guess strips
You really need to get yourself a decent FAS/DPD test kit (Taylor K2006c or TF Testkits TF100 in the states) to get accurate results as maintaining an appropiate shock level means testing quite often during the day and not just dumping shock in and thinking "that's it"
ritchie-t
Pool Enthusiast
Pool Enthusiast
Posts: 12
Joined: Mon 08 Aug, 2022 10:35
My Pool: 10X5 metre pool, sand filter.

Re: Alkaline and PH very low, CYA high.

Postby ritchie-t » Tue 09 Aug, 2022 03:41

Thank you for the help and advice on products. It sounds like a partial drain and refill is on the cards then. I will get an accurate test kit to make sure the CYA number is right so I know how much I am draining.
Denniswiseman
Pool Industry Leader
Pool Industry Leader
Posts: 2592
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: Alkaline and PH very low, CYA high.

Postby Denniswiseman » Wed 10 Aug, 2022 01:53

ritchie-t wrote:Thank you for the help and advice on products. It sounds like a partial drain and refill is on the cards then. I will get an accurate test kit to make sure the CYA number is right so I know how much I am draining.

To get things moving quicker use a pool store for your numbers
(Taylor K2006c or TF Testkits TF100 in the states)
ritchie-t
Pool Enthusiast
Pool Enthusiast
Posts: 12
Joined: Mon 08 Aug, 2022 10:35
My Pool: 10X5 metre pool, sand filter.

Re: Alkaline and PH very low, CYA high.

Postby ritchie-t » Fri 09 Sep, 2022 06:26

So it is confirmed that I do need to drain about 2/3 of my pool due to high CYA.

After reading up on draining pools and the dangers involved, I was curious to get peoples opinion on how much to drain in one go.

My pool is rendered and painted. I can only assume that because of the finish it would have to be a concrete pool behind the render? I am not sure what else could have that finish.

While the pool is inground, it is on a raised part of the ground from the "normal" garden level. I assume this helps with the hydroscopic pressure as the water table is likely to be low in comparison to the pool. It is also in Spain where it would not be difficult to find a time slot to do the job after a prolonged lack of rainfall when the water table would be very low.

Is the hydroscopic pressure from the water table the only concern for a concrete pool drain? Or are there other things that need to be taken into consideration?

I am hoping that I can get away with either doing the full 2/3 drain in one hit......... or my thinking is, if I am going that far and have confidence that the pool would be ok due to the location and climate, I may as well just drain the lot and refill. The tap water chemical readings on the property are very good, so a full refill would put me in a good place. It also gives the opportunity to give the render a fresh coat of paint.
Denniswiseman
Pool Industry Leader
Pool Industry Leader
Posts: 2592
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: Alkaline and PH very low, CYA high.

Postby Denniswiseman » Fri 09 Sep, 2022 06:54

Concrete pools are less likely to float unlike fibreglass so it may be possible to completely drain for maintenance
If you have a main drain then you could have a hydrostatic relief valve incorporated to allow groundwater to flow into the pool equaling the pressure
The only other concern is the render drying out
ritchie-t
Pool Enthusiast
Pool Enthusiast
Posts: 12
Joined: Mon 08 Aug, 2022 10:35
My Pool: 10X5 metre pool, sand filter.

Re: Alkaline and PH very low, CYA high.

Postby ritchie-t » Fri 09 Sep, 2022 08:34

Thanks Dennis,

I assume that the pool has to be emptied to fit the valve, so it doesn't remove the risk unless I want to future proof it for another day?

Apart from the risk of the render drying out. It sounds like I may be ok. After the dry summer months in Spain there is not much chance of the water table being near the bottom of the pool... famous last words!
Denniswiseman
Pool Industry Leader
Pool Industry Leader
Posts: 2592
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: Alkaline and PH very low, CYA high.

Postby Denniswiseman » Fri 09 Sep, 2022 09:08

What I'm saying is you may have a hydrostatic relief valve already if you have a main drain
A couple of YouTube Videos to get an idea
https://www.youtube.com/watch?v=sQi9FIf0_RU
https://www.youtube.com/watch?v=21G3eysPGSg
ritchie-t
Pool Enthusiast
Pool Enthusiast
Posts: 12
Joined: Mon 08 Aug, 2022 10:35
My Pool: 10X5 metre pool, sand filter.

Re: Alkaline and PH very low, CYA high.

Postby ritchie-t » Fri 09 Sep, 2022 09:20

I see. Good shout.

I will check it out... best practice holding my breath if I am going to take a look under the main drain cover with the pool water in :D
Denniswiseman
Pool Industry Leader
Pool Industry Leader
Posts: 2592
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: Alkaline and PH very low, CYA high.

Postby Denniswiseman » Fri 09 Sep, 2022 09:23

Don't forget to weigh yourself down as you won't be able to do anything

Return to “pH & Total Alkalinity”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 2 guests