Shocking SWG Pool???

[Bent6]

New to the board. Wealth of information here that the pool store will hate that I now know. I've always taken a water sample to the pool store and walked out at least $100 lighter in the pocket. It's always seemed like a moving target up until now. I've learned more about pool chemistry and how to adjust it in the two days I've been on this site than the entire 5 years I've owned a pool.

Just converted to salt this year. I've adjusted the chemical levels as follows:

Salt = 3300ppm
FC = 5
CC = 0.2
TA = 70
pH = 7.3
CYA = 70

According to the chlorine/cya chart the shock level for this pool would be around 28ppm. My question is - when raising the FC to this high of a level, how long will it take to come back down to a swimmable level? Should I turn off the SWG until it drops back to 5ppm?

In the past, I've always used either a 15min shock or non-chlorinated shock. How does a non-chlorinated shock even work? Do I even need to worry about shocking as long as the CC stays below 0.5?

 

[duraleigh]

when raising the FC to this high of a level, how long will it take to come back down to a swimmable level?

As are many answers on this forum, " it depends". A typical pool loses 2-3ppm daily of FC. Higher FC levels lose a little quicker so I would SPECULATE that it will take 3-4 days for your pool to return to correct levels if your current CYA is 28ppm. Pure speculation but I am probably pretty close. Incidentally, it is safe to swim in your pool at any level of FC up to and including shock level.

Naturally, shutting of the SWG allows your FC to come down more quickly.

 

[Bent6]

In the past I've always been advised to "shock" the pool every week, after high swim loads, after storms - this usually involved adding 3#s of Shimmer n Shock or a non-chlorinated shock. Pool is 26000 gals.

Do I even need to worry about shocking as long as the FC stays around 4-5 and the CC stays below 0.5ppm?

 

[jblizzle]

What you were previously doing was not the shock process as recommended here and described in Pool School. If your water is clear and CC < 0.5ppm and your SWG is maintaining FC without adjustment, then you should not need to shock. You need to go through the shock process if you seeing something is "off" ... for example, if FC drops, algae appears, CCs show up, etc.

 

[masand]

If in doubt, I would try an overnight FC Loss test as described here:
http://www.troublefreepool.com/pool-school/overnight_fc_test

Your current FC of 5 is fine so if it holds overnight (with the SWG off), you're good. I have had algae in my pool but the constant flow of Cl from the SWG masked/prevented a full bloom, causing the SWG to need to work harder to keep up.

If the overnight drop test fails, you should shock per the instructions in pool school. "Shock" isn't a product, its a process.

 

[Bent6]

Incidentally, it is safe to swim in your pool at any level of FC up to and including shock level.

Not that I doubt you or anything but, why do all of the test strips, pool stores, etc usually advise to wait until it's in the 3.5-3.8ppm range to swim?

 

[Butterfly]

Incidentally, it is safe to swim in your pool at any level of FC up to and including shock level.

Not that I doubt you or anything but, why do all of the test strips, pool stores, etc usually advise to wait until it's in the 3.5-3.8ppm range to swim?

well, it is because they do not understand the relationship between chlorine and cya.

welcome to the forum

 

[chiefwej]

I haven't had to shock my pool in six years. If you keep the levels balanced you may never have to shock it. If you have no CC, the water is clear, no algae or organic materials, there is no reason to shock. When you do need to add CL for any reason including shocking, liquid chlorine is always best.

 

[bobodaclown]

According to the chlorine/cya chart the shock level for this pool would be around 28ppm. My question is - when raising the FC to this high of a level, how long will it take to come back down to a swimmable level? Should I turn off the SWG until it drops back to 5ppm?

In the past, I've always used either a 15min shock or non-chlorinated shock. How does a non-chlorinated shock even work? Do I even need to worry about shocking as long as the CC stays below 0.5?

I like the chart on this page: http://www.poolsolutions.com/gd/best-gu ... chart.html

I think it's a pretty good guide.