Above ground pool CYA question

[UmmScott]

Hey everyone. I have a 30x30 round approx 23,000 gallon pool.

Last year was my first year with a pool. I educated myself and learned a ton. I bought the taylor FAS testing kit and utilized it.

I learned the issues with using too much trichlor and I think I am seeing this now.

I opened the pool this week. Its very green with algae. First test I did was CYA and its at 95.
So my CYA is high.
Alkalinity is 100
PH is 7.6
I'm unsure if I should deal with shocking right now and maybe use Floc?
I think it would be a waste to shock with the CYA being so high.

Could I Floc with the pool being green, do a partial drain and refill to get CYA in check and then proceed with chlorine?


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[Teapot1]

I would do a partial drain and refill first, that way you get rid of half the algae and wont be wasting chemicals you later dump.

[UmmScott]

I would do a partial drain and refill first, that way you get rid of half the algae and wont be wasting chemicals you later dump.

Thanks..

I will do a partial drain and refill.

Should I flocc at that point or would I be better off doing the SLAM after getting my CYA in check and not using flocc?

To daily chlorinate my pool I'll use trichlor in moderation along with sodium hypochlorite.

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[Denniswiseman]

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 Trichlor for when you need to chlorinate while on vacation or away for extended period of time

[UmmScott]

I did use alot of cal-hypo for shocking last year and at that time I was unaware of how to properly run my pool.
I am closely getting the hang of it.

I couldn't believe how much chlorine I had to use but that was because my CYA level was so high and I didnt know.

Do i need to worry about phosphate and calcium hardness levels?

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[Denniswiseman]

Phosphates can promote algae growth in high levels but at low levels not a problem
Calcium is necessary for plaster pools whereas liner or fibreglass it isn't necessary
High levels can cause scaling on the pool surface and affect the plumbing
Recommended Pool Levels

[Teapot1]

Phosphates can promote algae growth in high levels but at low levels not a problem

Whilst the guys on TFP may say that as their water is polluted anyway so not much they can do about it. Elsewhere getting phosphate levels down means when chlorine levels drop nothing much grows. Without chlorine the pool eco system takes hold and one thing feeds off another. Starve the water of phosphates and that process doesnt happen either.
My pool is often closed up for 10 months of the year without the water getting cloudy or algae swamp. With covid, didnt get there for 18 months, still clear when I opened up.
One of the benefits of Jollyjelly clarifier (other makes are available but may not have the same effect) is the reduction of phosphates whilst polising the water clarity (subject of clarity is slightly dependants on having the correct filtration rate and not a huge single speed pump on a tiny filter).
I am all for progressing the knowledge on pools and not just repeating bad and mis understood practices of old.

[UmmScott]

Update.

I did a 2/3 drain and refill of my pool. Alot of the Once it filled I got my pump and filter running for a couple hours to turn the water over.

I tested and had:
CYA: 30
Alkalinity: 90
PH: 8.5
Calcium: 120
FC: 0
CC: 0

I have not had phosphates checked but my water was looking way better.
I first lowered PH to 7.5 via muriatic acid. Let that sit for an hour circulating.
Later that night I began my slam process.
I used 1Lb cal-hypo at 56%.
After an hour that night I had 29ppm free chlorine and 0 combined chlorine.

Checked this AM
FC: 22
CC: 1.0

I will test again this evening and maintain my slam level. My slam level was supposed to be 12 with my cya level so i overshot it but i will keep it in check.
Pics attached. Making progress. [img]https://uploads.tapatalk-cdn.com/20230516/c556e8f9c7577ed2ebf757aef6dee169.jpg[/img][img]https://uploads.tapatalk-cdn.com/20230516/08952f0cbe40cad06ff0b9358883cbb6.jpg[/img][img]https://uploads.tapatalk-cdn.com/20230516/9217b644443d446688370e1f4f7f8c8c.jpg[/img]

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[Denniswiseman]

Don't panic about overshooting but keep checking to make sure it doesn't drop below the slam level

[UmmScott]

Update...

Tested last night and my FC was 9 with CC 0.5

I raised my FC level last night to 22.

This morning my FC was 9 again with 1.0 CC. I used bleach to raise it again to 12 to 13.
Will check again this evening. Water is clearing up and filter pressure is going up. So far so good with my slam

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[Denniswiseman]

It looks like it's doing it's job, keep checking
If the filter pressure is building up you may need to backwash to clear some of the dead algae

[UmmScott]

Update again. Pool is very blue and very clear.

I have backwashed twice. The first time the backwash wa was very very brown. The 2nd time I was fooled because I had no water flow so I backwashed. The actual cause was cotton sliming up the basket in the pump not the skimmer.
Cleaned that, theres still a bunch of cotton flying around in my area. Filter pressure is around 12psi to start. I think ill let it go and really try to catch more in the filter.

I decided to come down from the slam levels as 3 days in a row I had high FC and 0 to 0.5CC levels.

3 days post slam, currently using trichlor tabs and today I have...
CYA: 25
FC: 4
CC: 0
PH: 7.6
Alkalinity: 90
Calcium: near 200

I will use trichlor while monitoring my CYA and change methods as needed.
I think I have the hang of this!
I appreciate everything guys.

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[Teapot1]

Glad its all going in the right direction

[UmmScott]

So... I think I just had a realization and hope I interpreted this correctly.

We talk about "shocking" the pool being a process not a product.
Shocking simply means quickly raising our FC level and keeping it there breifly to "reset" and break up CC/chloramines correct?

That stated, if a pool is maintaining the proper FC level in relation to CYA and keeps 0 to 0.5ppm in CC/chloramines, then there is no need to shock? The FC is correct and is doing its job yes?

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[Teapot1]

Absolutely correct.