Recommended levels and gradual bleaching of dark colored liners

[Catanzaro]

My wife is not crazy about using the BBB method. She put something in front of me that reads as follows:

"If chlorine concentrations are above recommended levels (5.0 ppm for super-chlorination, or 10.0 ppm for shock) for long periods of time, gradual bleaching for most liners will occur"

Is there any validity to this? My levels spike up to about 7 ppm daily and reduce down to 4 ppm daily based on my CYA. My CYA is 40-50 (around 50) with minimum of 4 and target of 6. Because of daily loss, the 2 ppm difference is not sustainable. The pool will go through 3-4 ppm per day.

Any thoughts? Thank you.

 

[Casey]

Well sure but your FC is working closely with your CYA to make it a perfect balance and not harm your pool fixtures, pump n filter, your surface (liner) and most importantly, your skin. If you didnt have the CYA in the pool, it could most certainly bleach out your liner and harm your equipment n those who swim. The Sun is also a culprit of fading color out of the liners and clothes so it's not just chlorine that she needs to factor into the fading and or bleaching of a liner.

 

[Skitch]

The recommendation your wife showed you does not take into account the relationship between CYA and chlorine. It assumes 30ppm CYA.

Besides, even if it did promote gradual bleaching, that's far better than norovirus!

 

[tim5055]

No, because that statement does not take the effects of CYA into account. As long as you are below shock level based on the CYA level you are good to go.

 

[Richard320]

That's true only if there's no CYA in the water.

If you check out this thread or look at the chart below, you'll see how much of the actual bleach is "active: at various CYA levels.
https://www.troublefreepool.com/~richardfalk/pool/HOCl.gif

 

[scott39]

Great graph Richard.

 

[tim5055]

Great graph Richard.

if you like the graph, click on the link. Chem Geek does his homework on this stuff - truly amazing.

 

[scott39]

I have no doubt. Been reading a lot of Chem Geek posts. Being a chemical engineer myself, he is spot on!

 

[BuckeyeChris]

what is your wife's preferred method? Pucks? Because...those are pucks of chlorine. How would she know how many pucks, at flow rate, are giving her an adequate-but-not-too-much level of chlorine? Unless she can answer that, it's just as likely to bleach out the liner by mis-applying the pucks or cal hypo or whatever.

 

[Catanzaro]

She has no preferred method. Her Pool Guy told her this. She does not understand anything about CYA, FC, CC, TC, CH, PH, Pucks, Shock, etc.

I asked her nicely to have her Pool Guy (still unknown to this day & probably someone she works with) to come over so I can throw him in the pool head first in the shallow end (LMAO).

The water sparkles in the morning. It is crystal clear. The amazing part is that after the first season and the start of the second season, I have had absolutely no issues, while others that I know that are using Pucks, Frog System, etc. somehow tend to develop algae and spend a ridiculous amount of $$$$ on chemicals that are not needed.

If I listened to the pool company, I still be would using the Frog system, shocking my pool weekly, adding Phos-Free, and purchasing chemicals that cost 50%-75% more at the pool store then I can purchase at the local supermarket.

I actually worked out a deal on fresh 12.5% for $4 a gallon. This is not the norm here in NJ. Most places charge $6 a gallon. The batch was fresh and right off the truck. I took a friend along and we purchased 25 cases (4 gallons in each case) and enough to last the whole season for both of us. This making it less expensive then 8.25% at Wal-Mart.

BTW, my friend switched from Pucks to BBB after seeing the condition of my water.

 

[chem geek]

As noted here, it is only the medium shade blue color that uses an organic dye that is not particularly resistant to chlorine fading. It WILL fade with chlorine exposure and by UV exposure from sunlight. How long depends on the active chlorine level. More concentrated chlorine, particularly at lower pH, will cause faster fading which is why a Trichlor puck on the liner is the worst. Low pH by itself results in more wrinkling or causing the vinyl to become more brittle and this effect also depends on the amount of calcium carbonate "filler" used in the liner (see this post).

This article talks about the differences in colorfastness for inorganic vs. organic dyes, though in the context of colored pool plaster. Nevertheless, the principles apply to vinyl as well.

Colors that are resistant to chlorine fading are white, turquoise, light blue, grey and dark royal blue. It looks like your pool might be the latter (i.e. dark royal blue).

 

[Catanzaro]

Thanks everyone for their prompt responses. Enjoy your summer.