Another shock question

[alapool]

I have been running the Pool Frog system for the last 2 years and I have decided after reading thru this forum that I am going to try using the bleach method. Sounds like a pretty easy solution.

So as I understand it you add liquid bleach every 2 or 3 days depending on your chlorine level. I personally don't want my levels to be above 3 ppm. The question that I have is when do I shock the pool? And does "shock the pool" mean that you just add a lot more liquid bleach?

Thanks for any help!

And THANKS FOR THIS WEBSITE!!!

[JohnT]

You shock the pool when the combined chlorine gets above about 0.5ppm, and you do it by adding enough bleach to raise the chlorine to the desired level. That level depends on your pool construction and CYA level of your water.

[alapool]

Let's assume I have a CYA level of 30.

So does that mean that when the combined Cl level is at .5 ppm, then the FC level is usually below 1 ppm? and I need to add enough CL to raise the FC level back to 3 ppm?

[waterbear]

According to Ben's "Best Guess chart
http://www.poolforum.com/pf2/showthread.php?t=365
with a CYA level of 30 your min FC should be 3 ppm and your max 6ppm. This is the range you need to keep it at normally. If your CC is greater than .5 ppm you need to shock by raising you FC to 15 ppm.

You can have CC at any level of FC. It depends on whether there is enough 'reserve' of FC to 'burn off' the contaiminents in the water and break down the CC. If you have an outdoor pool without a SWG a CYA level of 30 ppm is a good choice.

Be aware that the pool frog is a silver/zinc system and had probably added metals to your water. You might want to read the section of the forum on metals
http://www.poolforum.com/pf2/forumdisplay.php?f=139

[duraleigh]

Let's assume I have a CYA level of 30.

So does that mean that when the combined Cl level is at .5 ppm, then the FC level is usually below 1 ppm? and I need to add enough CL to raise the FC level back to 3 ppm?

Hi,

You're on the right track, but off just a little.

1. If you are not willing to keep your Cl a little higher than 3ppm, you may have some problems. That's just not quite enough residual sanitizer to keep your pool sparkling. You'll need to keep it somewhere between 3-6ppm with a CYA of 30.

2. If your CC test indicates greater than .5, yes, you "shock" the pool by greatly increasing the Cl.....up to 15ppm (with a CYA of 30). That burns up all the bad stuff in your pool, eliminates any odor you may have had, and restores your pool to a healthy condition. You then let the Cl come back down to it's maintenance level of 3-6ppm.:) :)

Dave S.

[alapool]

Ok, so I have read a the threads on too much copper in pool. I'll take care of this in another thread.

What kind of effect should I expect with the FC between 3 and 6 ppm? Will it cause the liner life to go way down? Will it cause skin irritations? Will it cause hair to become "straw-like"? These are issues I want to avoid. And what level does my CYA need to be if I want to keep the FC down between 2 and 3 ppm?

Also, how long does it take for the FC levels to come back down to the normal levels after I shock? When is it safe to swim again?

Thanks a bunch for your answers!:)

[waterbear]

Will it cause hair to become "straw-like"?
Thanks a bunch for your answers!:) Having held both Barber and Cosmetologist licenses in the state of Florida for 29 years and having taught both professions I can tell you that it is NOT chlorine (at normal and even shock levels) that causes hair to become "straw like' but exposure to the UV rays of the sun. (You can sit by your pool and never go in the water and it will happen just as fast;)) Also chlorine will NOT cause the hair to turn green. That is from copper and I have outlined a safe and effective way to deal with that problem in another post
http://www.poolforum.com/pf2/showthread.php?t=326

[JohnT]

What kind of effect should I expect with the FC between 3 and 6 ppm? Will it cause the liner life to go way down? Will it cause skin irritations? Will it cause hair to become "straw-like"? These are issues I want to avoid. And what level does my CYA need to be if I want to keep the FC down between 2 and 3 ppm?

Also, how long does it take for the FC levels to come back down to the normal levels after I shock? When is it safe to swim again?



You won't even know there is chlorine in the pool at 3-6 ppm IF you keep your combined chlorine under control, which is easy. As to CYA levels, search for "Ben's Best Guess" on here and you will find details.

How long the FC will stay up is totally dependent on the situation. Sunlight, water condition, CYA level, bather load, cover use etc.. You are usually good to go the next day, but you need to test. I only shock about once or twice a year while we are swimming, so I don't have much to go on.

[CarlD]

Alapool:
You've gotten good advice here. You cannot rely on 3ppm as a max--as has been said, 3ppm is the MINIMUM for a CYA level of 30ppm--and running an outdoor pool with less than 30ppm of CYA is an invitation to an algae bloom--because chlorine will disappear due to breakdown and UV rays--sometimes in as little as 15 minutes.

You are probably looking at the EPA's rec that you don't swim in water above 3ppm of chlorine....Yet the same agency recommends that you don't drink water above 4ppm of chlorine--so at 4ppm it's not safe to swim in but it's safe to drink? Bit of a disconnect here, isn't there?

The minimum and maximum safe levels of chlorine depend heavily on the CYA level. Above 10ppm you can get some fading of bathing suits, but that's about it. Swimming pool liners aren't in danger until you reach 15ppm--but that is ONLY for low CYA levels. Again, the CYA affects the chlorine's action.

Your CC should always be zero. However, realistically, using Ben's kit, it frequently has a presence of less than .5--but unless you use the 25ml test (vs the 10ml test) you cannot tell if it's .2 or .4 or .5ppm. This could be due to pollen, suntan lotion--any slight contaminant--and it's hard sometimes to get that last bit of CC gone--I generally run my FC between 4 and 8ppm and that darn "<.5" shows up. But if it's clearly .5 or greater, you need to shock to get it down.

[Lenny]

However, realistically, using Ben's kit, it frequently has a presence of less than .5--but unless you use the 25ml test (vs the 10ml test) you cannot tell if it's .2 or .4 or .5ppm.

Carl,

Are you just talking about using the same test kit and just changing the proportions? I don't think I saw that listed as an option in the instructions.

Lenny

[CarlD]

If you look at the DPD-FAS test, there are two ways to use it:
1) with 10ml of pool water. Then each drop of the re-agent represents .5 ppm
2) with 25ml of pool water. Then each drop of the re-agent represents .2ppm, allowing greater precision.

[kjsmom]

What is the highest SAFE, NO FADE chlorine level for shocking an inground vinyl liner pool? Last Spring, I was advised on the forum that I could safely go up to 10-12 ppm chlorine for shocking, and I did maintain that level until the water cleared -- about a week.

In August we had a big storm and had to put a patch on the liner -- I was totally shocked at how faded my 2 year old liner was!

We replaced the liner last Fall, and I would like to preserve the color. I called Pacific Pools and was told not to go over 3ppm chlorine, (1 1/2 - 2 ppm chlorine for maintenance); that's a big difference.

If it took a week to clear the water at 12 ppm chlorine, how long will it take at 3 ppm chlorine (the water was pretty nasty dark olive green).
Pat

[aylad]

What is the highest SAFE, NO FADE chlorine level for shocking an inground vinyl liner pool? Last Spring, I was advised on the forum that I could safely go up to 10-12 ppm chlorine for shocking, and I did maintain that level until the water cleared -- about a week.

In August we had a big storm and had to put a patch on the liner -- I was totally shocked at how faded my 2 year old liner was!

We replaced the liner last Fall, and I would like to preserve the color. I called Pacific Pools and was told not to go over 3ppm chlorine, (1 1/2 - 2 ppm chlorine for maintenance); that's a big difference.

If it took a week to clear the water at 12 ppm chlorine, how long will it take at 3 ppm chlorine (the water was pretty nasty dark olive green).
Pat
It depends on your CYA level--at higher CYA levels you have to maintain higher minimum chlorine levels to keep your pool clear. See the "Best Guess" chart (first thread in this forum) for a guide on how high your Cl levels need to be.

Janet

[CarlD]

Pat:
Liners fade. There's nothing you can do about that. UV rays will simply fade all liners, regardless of chlorine. Chlorine levels at 15ppm with no CYA will fade them faster, that's all.

I can see how my liner faded in two years from the drop-in steps. That spot is darker than the rest. Good thing the steps will go back there again!

Would you rather slow down your fading by keeping chlorine below 3ppm or not have an algae bloom? That's really the choice. Truly, you are better off concentrating on keeping the water sanitary.

BTW, that 3ppm is nonsense--the pool liner company cites it because the EPA says that's the max swimming water should be for safety. Recommending higher levels than that may introduce a legal liability so that's all they'll say. Curiously, the same agency (EPA) says DRINKING water can be 4ppm, and even, under certain conditions, as high as 10ppm. So somehow, magically, it's safe to drink water that it's not safe to swim in....

[kjsmom]

Thanks Carl,

Yeah, I know the liner will fade over time -- I'd just like to keep the liner new looking as long as possible!

This statement confuses me though:

"Chlorine levels at 15ppm with no CYA will fade them faster, that's all."

I understand that the CL will fade the liner; what affect does "no CYA" have, other than the CL disappearing quicker? Aren't the CL shocking levels lower w/no CYA?

Thanks for your help.
PAT

[mwsmith2]

CYA inhibits the action of Cl. Pools with high CYA can go higher with the Cl and not have adverse effects on the liner.

Michael

[kjsmom]

Thanks again, Michael --
Every time I think I'm about to figure it all out, I learn something brand new about which I was totally clueless. I had absolutely no idea cya protected the liner from high chlorine levels.

So, since I kept my CYA around 30, and I shocked my pool at 12-15 ppm, could that be why my liner faded?

PAT

[mwsmith2]

The primary job of CYA is not to protect your liner from high Cl levels. It just happens to do so because it inhibits Cl action when it is present in significant quantities, as mentioned before in this thread. Your liner most likely faded due to age, as mentioned by CarlD, a few posts up. If I remember correctly, most liners can take 15 ppm with no problem, but that is the upper limit. Other liner pool owners may remember better than I.

Michael

[kjsmom]

Thanks Michael,
I understand about the cya. There was discussion in the "old" forum that a vinyl liner could take 15 ppm, and I did go that high last Spring in an effort to speed up clearing the water. I know liners do fade over time, but mine was only 2 years old, which I thought was pretty new.

Anyway, I have a new liner, (due to disastrous encounter late last summer with an umbrella during a storm), and I'm going to try to be more conservative with the chlorine. I'm going to try the 60-80 cya and 1-3 ppm cl called for in the Aquarite manual.

I am a little nervous about that because according to the "best guess" chart, 60-80 cya requires a minimum FC level of 5ppm. Maybe the numbers are different with the SWC (I hope).
PAT

[waterbear]

I have an aqulogic SWG and run my cya at around 80 ppm and my FC at 3 pm and have had no problems so far.