FC and optimal level for swimming.

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H

hoboryan

0
Jul 5, 2017
50
Canada
Hi,

I had an issue with algae a month ago and got the problem taken care of by SLAMMING it. Took almost a week and a half until it became clear. I made the mistake of reverting to chlorine dispenser/pucks (with stabilizer) to maintain my FC in the 5-7 range (CYA had dropped to 42 after I did a lot of vacuuming to waste to deal with the algae). Now my CYA is back up to 58 and I now maintain the FC in the 6-8 range.

When I told the pool store this, they were shocked and said that kids can't swim in chlorine this high. It needs to be 1-3 ppm. When I suggested that it was because my CYA was high, they didn't understand. My questions are:

1) Can kids swim in FC of 6-8 with CYA bordering on 60? Is this equivalent to a 1-3 FC range with 0 CYA?
2) Is the pool store right? or is TFP right? There's just so much conflicting information out there I don't know who to believe anymore. Some people just pay the pool guys to take care of it..and it seems to be wrong. How are these pool guys getting stuff done if they don't know what they're doing?

Regards,
Ryan
 
Yes, kids swim in pools with much higher active FC all the time. Just remember that a pool with CYA has a much lower active FC level than a pool without it. What you have discovered is one of the many reasons why we tell folks to stay out of the pool $tore. They really have no idea what they are talking about. All they do is parrot what they have been told by folks stuck in the dark ages.
 
Another issue is pool stores are the last place to get CYA testing, mine were off by over 100 most times. You really need to get some sort of accurate way to tell what your CYA really is or any advice is just guessing.
 
Ryan, read some of the threads here on TFP. You'll see/read about kids, dogs, parents, everyone swimming at much higher FC range than the pool store knows about and no one is harmed in the least. Pool store folks don't understand how CYA buffers the chlorine. If a pool has 12ppm of FC and CYA level of 30 it is actually less harsh than a pool with 2ppm of FC and NO CYA.

Having your pool chlorine out of whack to what your CYA stabilizer level is is just an invitation to algae to take up residence.

Our method has been practiced by thousands and thousands of pool owners. Science geeks have written much of the TFP protocol and can explain it in detail, and have been considered experts in the swimming pool chemistry field.

Its just a lot of common sense with science backing it up. Take a look at Pool School and learn how we do things.

Maddie :flower:
 
Welcome to TFP! Good to have you here :)

TFP is right, along with any pool techs that can explain the FC-CYA relationship properly.

Most pool industry people know that CYA protects FC from sunlight, but most don't know how it does that. Most also don't know that when CYA is present most of the free chlorine is tied up in the CYA-FC 'buffer' system as chlorinated isocyanurates. At 60 ppm CYA and 6 ppm FC, around 95% of the FC is tied up and only 5% is active chlorine, floating around as hypochlorous acid (the 'harsh' part of the active chlorine) and hypochlorite ion, which are the bits that can kill pathogens and algae. So your active chlorine would be about 0.3 ppm

By comparison, the water coming from your shower head at 1 ppm FC (allowable is up to 4 ppm), has 1 ppm of active chlorine (three times stronger than the pool)

A pool at 2 ppm FC and no CYA (typical indoor commercial or institutional pool) is 6 times stronger than the pool.

The pool is safe for swimming when:
You can see the bottom at the deepest point
pH is between 7.2 and 7.8
FC is at or above minimum for your CYA, per [FC/CYA][/FC/CYA]
FC is at or below shock level for your CYA, per same chart

As far as links, this one is helpful: Certified Pool Operator (CPO) training -- What is not taught
Note that a CPO course is 2 or 3 days and virtually nobody fails the exam.

Here's a few third-party articles:
New Thinking: Chlorine/Cyanuric Acid In Balance - AQUA Magazine
http://www.serviceindustrynews.net/journal/2016/2/15/cyanuric-acid-dictates-chlorine-levels
http://www.lowrycg.com/wp-content/uploads/2013/05/Cyanuric-Acid-It-Controls-Your-Pool-rev03.pdf

And if you enjoy the nitty-gritty: Pool Water Chemistry

Thanks for asking :) This is a big part of why many of us are here - to help keep residential pools and children safe.
 
I won't repeat what has already been said, except to reiterate that the above is correct. Rather, I have to ask, you do see the humor in asking in the TFP forum whether the pool store or TFP is correct, right? What answer did you expect? [emoji14]
 
Welcome to the forum Ryan!

Think about all the bottles of 'potions' in a pool store. The phos-free, clarifiers, flocculants, algaecides etc, with ingredients that most of us can't even pronounce correctly. Not to mention the overpriced baking soda (Alkalinity increaser), and borax (pH+). Do you really want your family swimming in a chemical stew?

All we ask is that you maintain the proper FC level based on your CYA level. Sodium hypochlorite, aka bleach, will be what you add daily to keep your water sanitary and crystal clean, 24/7. Of course you may also need a bit of muriatic acid to keep pH from rising.

My pool's pH is rock solid. The only additional things in my water are chlorine & CYA. It's so clear I can count the bristles on my brush in 4 feet of water.

IMG_0513.jpg
 

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Other than you do not need to maintain that high of FC for a target level, no. You will use additional chlorine due to increased UV loss, but the swimmers will never know the difference.
 
pH will effect your skin. Or CC's. But not FC within the [FC/CYA][/FC/CYA] range. Even up to shock level.

I maintain my FC at or just below 10% of CYA. People that visit cannot believe how pleasant the water is while swimming.
 
Yeh for skin, home in on pH first. Anything under 7.2 or over 7.8 can lead to itchy skin and eye irritation.

The other thing is salt. Tears are around 6000 ppm salt, and if you swim underwater with your eyes open, you're probably swimming in water that's around 1000 ppm, or if you have a salt water pool, around 3500 ppm salt. So the pool water lowers the salt content. Blinking instead of rubbing when you come up for air is the most effective cure for that. Bringing the salt level up to 2000 or 2500 helps some folks. The salt will not affect any of your other water chemistry and below 3000-3500 hardly anyone can taste it. The ocean is around 35000 ppm salt.

Some people run low CYA so they can protect equipment warranties and keep their chlorine under 4 ppm FC. This is just a game re: warranty. Nothing recommended here will cause any equipment or vinyl problems, because of the buffering effect of CYA. The trade-off as Marty mentioned is more FC UV depletion, but you get around 80% of the sunscreen effect at 30 ppm CYA, so depending where in Canada, that might be plenty. Everything here at TFP is about maximizing swimmer comfort and safety, longevity of equipment, and dollars kept in wallet. Hence the 145,000 TFP members!

Can't help you with the perceptions and popular culture regarding chlorine. Despite it coming out of your shower head stronger, being the most up-to-date water sanitizer, and probably contributing as much to life-span as vaccines and antibiotics, people are going to believe what they want to believe! Probably the most effective method for convincing people is not to say a word about the chlorine level, haha! :) They'll just tell you the water feels great, and you can leave it at that.
 
mknauss said:
Other than you do not need to maintain that high of FC for a target level, no. You will use additional chlorine due to increased UV loss, but the swimmers will never know the difference.
Click to expand...
And even this isn't necessarily true. A higher cya level will protect a higher percentage of your FC. In fact at a higher cya level you should be able to add fewer PPM to the pool every day to maintain adequate FC.

For example, at a low cya your daily FC may drop from 5 to 2. But at a higher cya your FC May only dropped from 7 to 4.5
 
jblizzle said:
A higher cya level will protect a higher percentage of your FC. In fact at a higher cya level you should be able to add fewer PPM to the pool every day to maintain adequate FC.

For example, at a low cya your daily FC may drop from 5 to 2. But at a higher cya your FC May only dropped from 7 to 4.5
Click to expand...

^^^Best explanation ever

worthy of no. 37000!!!
 
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