High CYA

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jcaj558
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High CYA

Postby jcaj558 » Wed 15 Jul, 2020 11:24

My cya is around 170 which I understand is really high. My pool company claims that a good cya range is 30-200. From what I read 30-50 is a good range. Do I need to do a partial drain? I use the 3 inch pucks for chlorine. Isn't the cya just going to go back up? Not sure what to do. Don't know if this makes a difference but my weekly chemical maintenance is 2 pounds smart shock, 4oz algae all, and 10oz pool complete.


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Re: High CYA

Postby Denniswiseman » Wed 15 Jul, 2020 13:22

For a start you are guessing what to put in your pool
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
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
Don't use copper algaecide as the effects aren't always desirable. Use a Polyquat 60
(Any brand as long as the ingredients are "Poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride" at 60% concentration.)
Check out these articles
Chlorine / CYA Chart,
Recommended Pool Levels
Use these common products to balance your pool
Liquid chlorine (sodium hypochlorite or plain bleach)
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
Use Pool Maths to work out how much to use
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Re: High CYA

Postby Ritch » Sun 30 Aug, 2020 15:10

Hi Dennis, sorry but I'd like to jump in on this thread if I may. I have a similar problem and am relatively new to pools and their chemistry. This summer I was having to feed the pool large amounts of chlorine to even get a reading (manual chemos balancing, was only measuring the basics). After googling and googling I purchased a Poollab 1.0 soI could test more than just PH and Chlorine. It turned out my CYA was off the limits, a diluted measurement showing around 190 ppm. I diluted the pool water bit by bit and got it down to around 120 ppm, but was advised to empty over half of the pool to get things back to 30 - 50 ppm. Having done this, I tested the water which came in just over 50 ppm. I then shocked the pool with liquid chlorine and added a slow tab. Now my CYA is already up to over 70 ppm! I googled the ingredients of the liquid chlorine and to my surprise it contains CYA (it was hidden behind a brand name). The tabs contain it also. How do people retain a low CYA if using stabilised chlorine? If I was to start with a CYA of between 30 - 50 ppm, wouldn't it quickly rise simply by adding the weekly slow tab and occasionally shocking the pool? (you're figures above seem to suggest this) Given it doesn't breakdown, I don't understand how to keep the CYA low. I assume using non stabilised chlorine for shocking might help but I'd really appreciate some advice. Many thanks in advance! PS: I'm in Switzerland so probably won't have access to the products you refer to.
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Re: High CYA

Postby Denniswiseman » Sun 30 Aug, 2020 16:21

Hi Rich
Having read my previous post and read the links you are half way there
Don't use any form of stabilised chlorine Trichlor / Dichlor but plain bleach (laundry) not the scented or thick type
All sodium hypochlorite (bleach) puts in the water is salt which isn't a problem
If your CYA drops to far from backwashing, rain and splashout you can use your stabilised tabs to boost it up again
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Re: High CYA

Postby Ritch » Tue 01 Sep, 2020 02:40

Thanks Dennis :thumbup:. I have found a couple of pool specific, liquid sodium hypochlorite products I can purchase locally. How do I get around the use of slow dissolving pool tabs? I don't have an automatic chlorine dispenser which would mean having to add liquid manually every couple of days right? I am still wondering how others can maintain a low CYA, as most people (around here at least) are using stabilised tabs to disinfect?
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Re: High CYA

Postby Denniswiseman » Tue 01 Sep, 2020 04:47

So long as you boost to the target range and don't let it fall below your minimum you should be fine dosing it manually. Testing will determine the frequency of dosing bearing in mind you can swim up to shock level for your CYA
Your tabs can be saved for boosting your CYA or for when you aren't available to do so
They won't have a low CYA and are probably blissfully unaware of the consequences of excess CYA on there sanitation
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Re: High CYA

Postby Teapot » Tue 01 Sep, 2020 21:40

Buy a basic chlorine doser if you can and life becomes so much better.
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Re: High CYA

Postby Ritch » Wed 02 Sep, 2020 06:23

Appreciate the prompt replies and the advice! Many thanks.
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Re: High CYA

Postby tbenton » Wed 28 Jul, 2021 10:36

We have had our pool since 1987 and always put our chlorine tabs in the skimmer and always have high CYA so we back off on the number of tabs. The tabs dissolve really fast in the skimmer. I was finally convinced to use a floating dispenser but it kept getting stuck in the skimmer and was advised to tether it. We tethered it to the spring under the diving board on about 3.5 feet of cord but it doesn't move very far from the edge of the pool. Its between the two jets but the jets are more than arm length under the water so not 'pushing' the floater. The tabs are hardly dissolving at all which may be a good thing but I want to make sure I am not doing anything wrong by having the floater just sit there but like I said...letting it roam freely always results in it getting stuck in the skimmer opening. What can I do and thanks.
Denniswiseman
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Re: High CYA

Postby Denniswiseman » Wed 28 Jul, 2021 12:39

Liquid chlorine (sodium hypochlorite or plain bleach)
Only use tabs to back up your CYA or when on vacation

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