CYA / FC debate

[dfwnoob]

It's turtles all the way down.

 

[ajw22]

What does this turtle stand on?

Principle!

 

[AUSpool]

So, here's my dilemma: I live in Las Vegas- extremely low humidity, high temp, direct sunlight on pool every day. I was told that 90% of FC in pool could be lost in one hour, due to direct sunlight UV radiation. CYA is a way to combat this, and prolong FC in your pool, but has it's downsides, described above.

If the goal is to have a Constant FC level of 2.0 ppm, but low-to-zero levels of CYA, I can't see any way of achieving this without an automatic, constant feeder. What am I missing?

I have a 12,500 gallon pool. I shock with Cal-Hypo 73%. I use Tri-Chlor tabs in a floater, but cannot keep FC sufficient w/ out shocking. I just drained, refilled pool 30 days ago, so high TDS or CYA are not issue. TA=90, CYA=15, pH=7.6.

Any advice would be extremely helpful!!
Mack

If its your pool your managing I would follow TFP’s CYA/FC chart. Its ironic that a higher FC target with the corresponding CYA level actually results in a lower and more consistent active chlorine (HOCl) level.

And your very right, automation makes it so much easier. While there are many that manually dose a chlorinator or peristaltic pump for bleach makes pool management so much easier.

But there are more benefits from stepping outside the industry standards. The equivalent concentrations or levels as given before by @mgtfp are more that just a ratio, they are due to the substitution reaction between the active FC (HOCl) and CYA where 97% of the active FC is bound to CYA as a chlorinated cyanurates which are mostly non reactive. This reaction, given very basically as FC + CYA <—> HCy-Cl is reversible, dependant on concentrations, where active FC is released from the chlorinated cyanurates to replace active FC that is used on the lefthand side of the equation. I provides a reserve of active FC.

Another benefit is flexibility with pH. If you compare the logarithmic concentrations of HOCl, OCl- and HCy-Cl the concentration of HOCl is not as dependent on pH as it is without CYA. Traditionally pH is maintained to maximise HOCl but with CYA the pH can easily be managed up the 7.8 which reduces HCl use and allows a bit more wiggle space to maintain CSI.



In your pool I wouldn’t be using cal-hypo or pucks, I would just use bleach. I have alway been cautious about the effects of anything I put in my pool.

So much of this is theoretical but in practical terms I have been following TFP’s methods for around ten years and have never needed to shock or SLAM my pools, and I haven’t always been as diligent as I should.

 

[PoolStored]

What does this turtle stand on?

A post.

An old Rancher is talking about things that aren't quite right with a young man from the city. He shares that those things are "post turtles." The young man doesn't understand and asks him, "what is a post turtle?"

The old man says, "When you're driving down a country road and you see a fence post with a turtle balanced on top, that's a post turtle. You know he didn't get up there by himself. He doesn't belong there; you wonder who put him there; he can't get anything done while he's up there; and you just want to help the poor thing down."

 

[AUSpool]

It’s missing the giant turtle on whose back the flat Earth rests as it transits around the sun …. basic cosmology really.

Disadvantaged again, being down under we squashed between the flat earth and the turtle, is that where the term ‘between a rock and a hard place’ comes from?

 

[Andy49]

The turtle goes all the way down. I bet you did not know that.

 

[Rocket J Squirrel]

Pool water is like the turtle. It goes all the way down and you have to feed it every day.

 

[ye olde salt]

What does this turtle stand on?

It's turtles all the way down.

 

[SoDel]

The flat earth got so much attention, how about when the sun revolved around the earth? Fun times! Aristarchus and Aristotle started debating this in 230 B.C. Aristotle won that argument (heh, c’mon, just use what everyone knows and your everyday experience; the sun has to revolve around the earth). It took only about a short 2,000 years to pass before this impertinent Galileo dude came along to be able to show that idea was almost certainly wrong. He was generously rewarded by being given the choice to either recant or die, and spent the remainder of his life under house arrest with his pet turtle.

 

[JamesW]

He was generously rewarded by being given the choice to either recant or die, and spent the remainder of his life under house arrest with his pet turtle.

Galileo fared better than Giordano Bruno.

Starting in 1593, Giordano Bruno was tried for heresy by the Roman Inquisition

The Inquisition found Giordano Bruno guilty, and he was burned at the stake in Rome's Campo de' Fiori in 1600.

Few astronomers of Bruno's time accepted Copernicus's heliocentric model.

Among those who did were the Johannes Kepler (1571–1630) and Galileo Galilei (1564–1642).

 

[SoDel]

Galileo fared better than Giordano Bruno.

Starting in 1593, Giordano Bruno was tried for heresy by the Roman Inquisition

The Inquisition found Giordano Bruno guilty, and he was burned at the stake in Rome's Campo de' Fiori in 1600.

Few astronomers of Bruno's time accepted Copernicus's heliocentric model.

Among those who did were the Johannes Kepler (1571–1630) and Galileo Galilei (1564–1642).

Burn at the stake — well that’s one way to reduce dissent Sadly for Bruno, he was a contrarian on a variety of questions and that just cheesed off the Romans. His ashes were thrown into the Tiber River where they came to rest upon a turtle‘s back.

To my way of thinking, it was Galileo who could and did first back the heliocentric model with solid evidence (as best I can figure out anyway). Copernicus probably could, but if he did he would have ended up like Bruno — ultimately ashes. On the back of a turtle.

 

[Newdude]

and spent the remainder of his life under house arrest with his pet turtle.

Cabin fever did him in and he became a recluse. At that point, the world outside was terrifying, especially things like bad weather.

 

[PoolStored]

Saw this in the cove today!!

 

[SoDel]

Sorry guys and gals but I think we got some of the details wrong. If you dig a little deeper, the earth appears to be a hemisphere resting on elephants. Resting on turtles. All the way down.

 

[Poolnerdgrandma]

It’s missing the giant turtle on whose back the flat Earth rests as it transits around the sun …. basic cosmology really.

What does this turtle stand

It's turtles all the way down.

Beat me to it.

 

[Gary Davis]

The key distinction between a commercial and residential pool is bather load and bather composition. In a single family residential pool, there is only one set of people with a unique set of health issues that uses the pool and they use the pool rarely (low bather load). In a commercial pool, you have hundreds of different bathers all with varying health conditions using the pool. Therefore the bather load is very high and so is the risk transmitting water born illnesses. So commercial pools need to keep their water bodies highly sanitized and they must respond to incidences very rapidly. Recreational water illnesses (RWI’s) are a serious hazard for bathers, not just an inconvenience and so that necessitates a very different set of standards for care. Water treatment for clarity and safety is also very different when you look at a residential pool versus a commercial pool. So the use of CYA is necessarily going to be more carefully scrutinized in a commercial pool setting.
And that’s the crux of it - you can’t apply standards meant for a commercial pool to your own personal pool, it just won’t work.

I don't have anywhere near the technical knowledge of the other people who posted in this thread, but I do want to say MY pool is, as described above, COMPLETELY DIFFERENT from a commercial pool (in keeping with what @JoyfulNoise is trying to impart).

• There are only two bathers (both of whom swim nekkid')
• Usually after the obligatory (albeit brief) cold-water garden-hose shower set up on the perimeter
• Neither of whom uses creams or oils (and we both use the same shampoo even)
• And never do we pee in the pool (heaven forbid we'd put soiled diapers into the pool)
• No pets (but maybe a bird poop & a floating mouse once in a while, along with leaves)

As noted by the others, the bather load is well controlled, to the point that we assess the risk of Cryptosporidium, Pseudomonas, Legionellae, etc., is (we consider) rather slim (although not zero).

Our simple philosophy is to maintain sanitation disinfection and carbonate balance at all times, with sanitation being mainly two components (FC to CYA ratio) and balance always a combination of a half dozen but mainly two components [(carbonate alkalinity to calcium hardness ratio) although temperature & pH equilibria have undeniably huge effects on the saturation index].

For simplicity, we don't use pucks - just HASA liquid chlorine & HASA acid & granular CYA & granular Calcium Chloride (and that's about it for chemicals).

What we do NOT do is follow Draconian commercial policies - as we follow reasonable sensible residential recommendations (which is why I'm on this forum).
To learn.