Balancing Pool Myself

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The test strips are not a test. They are a guess. Please do not use them to determine water chemistry.
 
One piece of info which may help you understand all of this, is that Chlorine is a gas, not a solid. This is why you can't get pucks, or granular, chlorine only products. It has to be bound with something to become a solid. It's bound with CYA for Di-Chlor and Tri-Chlor, and bound with Calcium for Cal-Hypo. Liquid chlorine is better because it's bound to sodium ... so you do add some salt into the pool when using liquid; but that is much, much, much better than adding CYA or Calcium every time your chlorinate.

With CYA of 160, 9.4 free chlorine is no where near enough to keep the water sanitized. ie: Is it NOT too high, but is actually too low. At 100 CYA, you would need to maintain 11 - 13 FC to have properly sanitized water. This is why your pool guy was adding shock on a weekly basis, because your FC levels are not high enough to keep algae away.

Have you seen the FC/CYA chart yet? Check it out here: Chlorine / CYA Chart - Trouble Free Pool

As far as dropping the hose in .... to cut that 160 CYA number in half, and bring it down to 80 ... you would have to exhcange 1/2 of your pool water ... so 5500 gallons (according to your signature details).

And ya, the test strips are not accurate.
 
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ejs873 said:
9.4 seems really high to me. There is no odor of chlorine at all and we have never had red eyes or burning. Any thoughts? Is 160 CYA high enough to need to drain the pool some? I really would like to avoid that but if i start getting algae then i will have no choice.
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The chlorine in a pool does not have an odor, and it will not irritate your eyes either. What you're smelling when you smell that "chlorine smell" is actually chloramines, when the combined chlorine levels are too high. And the chloramines are also what causes the eye irritation. That smell is a sign of water chemistry problems, not a sign of too high free chlorine.

And yes, you really need to exchange water. Most likely 1/2 of the pool's volume.

Check out the "No drain water exchange" section of this document.

Draining - Further Reading

www.troublefreepool.com www.troublefreepool.com
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Stoopalini said:
One piece of info which may help you understand all of this, is that Chlorine is a gas, not a solid. This is why you can't get pucks, or granular, chlorine only products. It has to be bound with something to become a solid. It's bound with CYA for Di-Chlor and Tri-Chlor, and bound with Calcium for Cal-Hypo. Liquid chlorine is better because it's bound to sodium ... so you do add some salt into the pool when using liquid; but that is much, much, much better than adding CYA or Calcium every time your chlorinate.

With CYA of 160, 9.4 free chlorine is no where near enough to keep the water sanitized. ie: Is it NOT too high, but is actually too low. At 100 CYA, you would need to maintain 11 - 13 FC to have properly sanitized water. This is why your pool guy was adding shock on a weekly basis, because your FC levels are not high enough to keep algae away.

Have you seen the FC/CYA chart yet? Check it out here: Chlorine / CYA Chart - Trouble Free Pool

As far as dropping the hose in .... to cut that 160 CYA number in half, and bring it down to 80 ... you would have to exhcange 1/2 of your pool water ... so 5500 gallons (according to your signature details).

And ya, the test strips are not accurate.
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Thanks. All of these numbers make sense, its just hard to justify draining the pool when I have never had any algae or water issues. I do think the CYA liquid test is subjective to your surroundings, so I will try it again in the sunlight. If it shows closer to 100 like the strip did ( I know everyone hates the strips, but it was a quick way to get an estimate) then I think i will continue to dilute the water some and add liquid chlorine as needed. Also I will need to add acid since we have high PH water here. Does the Acid affect the chlorine at all?
 
Stoopalini said:
No, Muriatic Acid won't affect your chlorine.

Post the full set of test results please. What is your calcium level?
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Just redid the tests:

PH - at least 8
Acid Demand 5 drops
Calcium 390
Free Chlorine - 7
Combined - 0.2
CYA - Just about 100, redid the test in the sunlight, black dot disappeared (to me).. right over 100 on the scale
 
ejs873 said:
9.4 seems really high to me
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In another thread, I did bit of a longer explanation why the higher, CYA-depending, chlorine levels that TFP recommends, are required and safe:

mgtfp said:
Unfortunately, the pool industry never bothered to understand the chemistry of CYA. They understand that CYA protects chlorine from UV by business building a chlorinated CYA-molecule that is a lot more resistant to UV (still not 100%).

The question that arises (and that you would expect pool professionals to ask themselves) is: If chlorine is building a relatively strong bond with CYA, is it actually still effective as a sanitizer and oxidizer?

The answer is NO.

The chemistry has been described in 1974 by a guy called O'Brien. It is available here on the forum via the search for those interested in chemistry.

Simplified in a nutshell: Between CYA and chlorine is an equilibrium reaction going on, where the vast majority of the chlorine is in a bond with CYA, and only a small fraction remains "active" chlorine (chemically: HOCl). This active chlorine does all the sanitation, killing algae, oxidizing sweat, etc. In doing so, the active chlorine is turned into salt (Cl-). That means the equilibrium between chlorinated CYA and HOCl is disturbed, and some chlorine gets released from CYA to become active chlorine (pretty much immediately). You can therefore think of the chlorinated CYA as "reservoir" chlorine.

This equilibrium also keeps working in your FC test: The changing colours in the test basically inactivates the active chlorine, more chlorine gets released from the "reservoir", gets inactivated by the test chemicals, and so on until all the reservoir chlorine eventually shows up in the test (all of this is happening within fractions of a second).

Therefore all of the active and reservoir chlorine together test as "free" chlorine (FC). But "free" doesn't mean active. "Free" is just used to differentiate from "combined" chlorine (CC), which is an intermediate product in the oxidization process of things like sweat or urine.

That's the misunderstanding in the pool industry: They work on the principle FC = AC (I just call active chlorine AC for now, that's just me, not an official abbreviation).

Ideal would be to test directly for AC. But that is not really possible in a residential pool setting. The next best thing is what TFP is doing. Test for FC and CYA, and then calculate AC based on above mentioned O'Brien paper. That's the basis for TFP's FC/CYA-chart.

The takeaway message is that the FC/CYA ratio needs to remain about constant to keep the active chlorine amount constant. If you double your CYA, you also have to double your FC to keep your pool in shape.

That also means that it is perfectly safe to maintain higher FC levels following the FC/CYA-chart. The reservoir chlorine is not aggressive to swimmers or pool equipment.

In fact, 3ppm FC without CYA is far more aggressive than our SLAM-level FC. If you wanted to maintain a pool without CYA, you actually needed to maintain an FC of something like 0.6ppm. That's incredibly difficult as you constantly have to replenish chlorine lost to UV and bather-load without overshooting. Not impossible, but challenging and not cheap. This is for example how things have to be done in public pools in Germany.

But it is far easier and economical, especially in a residential pool setting, to add CYA and increase FC according to the FC/CYA-chart to have a nice, non-aggressive (moderated), chlorine reservoir. TFP even recommends a small amount of CYA in indoor pools (where you don't have losses due to UV), just for the reservoir effect.

Next time, a pool professional goes crazy seeing your 6 or 8ppm with CYA, ask him if he'd be concerned about 3ppm without CYA - that's where I'd be concerned, as it is just unpleasant to swim in such water. Unfortunately that's what most indoor public pools do, and why you smell like chlorine even after showering, and why your swimsuits disintegrate so quickly in public pools.
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With your CYA of 100ppm, you are just above the min FC of 8ppm. Better to keep it between 11-13, even. As long as you never ever drop below FC 8ppm, a pool can theoretically get maintained at CYA 100ppm. But TFP doesn't recommend to do that, because if you do drop below the min FC and an algae bloom starts, it will take a lot of chlorine to maintain the required SLAM FC of 39ppm - there is nothing wrong with FC 39ppm at CYA 100ppm, it is perfectly safe, even to swim in, you wouldn't notice a thing (the CYA of 100ppm moderates the chlorine, I wouldn't want to swim in FC 39ppm with significantly less or even no CYA) - but it requires immense amounts of chlorine to maintain this level until all the algae is dead, which is not practical and expensive.

Have a look at the FC/CYA Levels.
 
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mgtfp said:
In another thread, I did bit of a longer explanation why the higher, CYA-depending, chlorine levels that TFP recommends, are required and safe:




With your CYA of 100ppm, you are just above the min FC of 8ppm. Better to keep it between 11-13, even. As long as you never ever drop below FC 8ppm, a pool can theoretically get maintained at CYA 100ppm. But TFP doesn't recommend to do that, because if you do drop below the min FC and an algae bloom starts, it will take a lot of chlorine to maintain the required SLAM FC of 39ppm - there is nothing wrong with FC 39ppm at CYA 100ppm, it is perfectly safe, even to swim in, you wouldn't notice a thing (the CYA of 100ppm moderates the chlorine, I wouldn't want to swim in FC 39ppm with significantly less or even no CYA) - but it requires immense amounts of chlorine to maintain this level until all the algae is dead, which is not practical and expensive.

Have a look at the FC/CYA Levels.
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Thanks for the info. So who knows what the FC was last summer when they were dumping shock in every week. I have never seen any algae so I'm not super concerned with draining the pool. Since I canceled the "pool guy" and started buying liquid chlorine, I might pump some water out and add more at the same time, so my levels don't drop. Once I can get the CYA down I'll start using the liquid chlorine. I do need to add some acid today since the pH is high. Thanks again
 

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ejs873 said:
Thanks for the info. So who knows what the FC was last summer when they were dumping shock in every week. I have never seen any algae so I'm not super concerned with draining the pool. Since I canceled the "pool guy" and started buying liquid chlorine, I might pump some water out and add more at the same time, so my levels don't drop. Once I can get the CYA down I'll start using the liquid chlorine. I do need to add some acid today since the pH is high. Thanks again
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A partial drain is certainly the way to go.
 
I thought this was amusing. After I canceled my pool guy they sent an email asking for feedback. I expressed my concern over the high CYA levels and their continued use of shock and tabs. In their response they said "as your CyA levels will rise again once thermal heating starts up in the next 60 days". Is there any truth to this? Does the sun and warm weather really increase the CYA levels?
 
Ha, the only thing that increases CYA is if you add it.

I guess if you only use chlorine that contains CYA, technically your CYA would go up when the water warms up... due to the fact that you are adding more CYA containing chlorine :hammer:.
 
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ejs873 said:
I thought this was amusing. After I canceled my pool guy they sent an email asking for feedback. I expressed my concern over the high CYA levels and their continued use of shock and tabs. In their response they said "as your CyA levels will rise again once thermal heating starts up in the next 60 days". Is there any truth to this? Does the sun and warm weather really increase the CYA levels?
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No, the sun and/or warm weather will not increase CYA.

This is very common from pool maintenance companies though. Since they only service pools once a week, they have to use some sort of chlorine product which time dissolves. So that's pucks ... and since pucks contain CYA, using them raises the CYA level. The reason they shock once a week is because the CYA level quickly gets so high, algae will bloom if you don't spike the chlorine levels on a regular basis.

In the winter, less chlorine is required, so less pucks are used by their service. When the water warms up, more chlorine is required, so more pucks are used by their service.

So from their perspective, warm water means rising CYA levels ... but that's only because they're using chlorine products which contain CYA.

It's not practical for them to use liquid (which does not contain CYA) because they would have to service the pool everyday if they did that.
 
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You made the right decision in getting rid of the pool service. Without a SWG, pool guys rely on tablets to keep your FC levels within range. As you found out, tablets continue to raise CYA levels to a point that the pool can no longer be maintained.

You can manage your pool with a CYA of 100. CYA levels do decrease slowly over time. As mentioned previously, keep your FC in the ranges shown on the FC/CYA Levels. Keep in mind that the pH test becomes invalid at FC levels above 10 ppm. Since your minimum FC level is 8 ppm, it's best to test pH before you add chlorine when FC levels are below 10 ppm.
 
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Rancho Cost-a-Lotta said:
You made the right decision in getting rid of the pool service. Without a SWG, pool guys rely on tablets to keep your FC levels within range. As you found out, tablets continue to raise CYA levels to a point that the pool can no longer be maintained.

You can manage your pool with a CYA of 100. CYA levels do decrease slowly over time. As mentioned previously, keep your FC in the ranges shown on the FC/CYA Levels. Keep in mind that the pH test becomes invalid at FC levels above 10 ppm. Since your minimum FC level is 8 ppm, it's best to test pH before you add chlorine when FC levels are below 10 ppm.
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Thanks. My goal was to keep the chlorine low in this pool so I just ordered a submersible pump and will pump out 4-5000 gallons and refill at the same time, to keep my levels the same. I am glad I found this website otherwise I would have kept paying the pool guy $100 a month to trash my water!
 

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