Oops. Overshocked pool

Rogers877

New member
Jun 15, 2019
4
Florida
I have run into a small problem. My pool had developed a persistent mustard algae problem ...it wasn’t bad but it was bothersome and growing.. .so I decided to go nuclear, triple shocked the pool on Tuesday with liquid chlorine. Mustard algae nuked -but the chlorine level is still very high...off the charts high. It is now Saturday and I’m still definitely over 10 ppm FC

We have had a few cloudy days but I’m concerned now. We want to resume use of the pool but it’s been 4 days.

How long do you guys think until FC falls back into normal range < 5 ppm? Evidently I used too many nukes

Salt chlorinator has been off since shock event
cya 70
Ph 7.5
15k gal
Water temp 78
Air temp 80-90
 

woodyp

Mod Squad
TFP Expert
LifeTime Supporter
Apr 17, 2010
10,491
East Texas
Your SLAM level for 70 CYA is 28. Don't worry if you're not over that! A fas-dpd chlorine kit is needed to test for levels that high. Available at TFTestkits.net It's part of the TF100 complete test kit which we recommend.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,267
Franklin, NC
A one time "shock" is not the solution to an algae problem. We at TFP do not "shock" our pools, we follow the SLAM Process when there is a problem.


You say your FC is "definitely over 10 ppm " We would recomend you get yur own quality test kit that will tell you exactly what your FC is.
Order a TF100 test kit


The only other real option for a test kit is a Taylor K-2006-C. Be careful comparing prices because the K-2006 comes in sizes, designated by a letter. The basic K-2006 has .75oz bottles. You need to get the K-2006-C to get the larger bottles that you want. Even then it is a little short on the reagent & powder for the FAS/DPD test.

While entirely optional, I also have the SpeedStir and Sample Sizer. They speed testing and accuracy.

If you purchased a Taylor K-2006 (even the "C" version), you will not have sufficient FAS/DPD testing reagents to complete a SLAM.

How much Pool School have you read? Start with these:





So, welcome to TFP!!
 

Rogers877

New member
Jun 15, 2019
4
Florida
ThAnks for the quick replies . Will order new test kit right now. Also the slam chart helpful...seems like shocked ok but I had been underchlorinating which may explain the algae issue

How much natural chlorine loss per day would you guys expect given my current levels of cya and an fc that is very likely 15-20+ ppm? We are trying to forecast when we can reopen
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
20,185
Laughlin, NV
What do you mean by 're-open'? IF your CYA is 70 and IF your FC is 20 ppm, go swimming. The FC is under the shock level of 28 ppm.
 

Rogers877

New member
Jun 15, 2019
4
Florida
IF is the operative word :) bc my testing kit may be a piece of junk. but it will be accurate on FC < 5. My FC could be 35 for all we know. Hence the question how how much natural ppm depletion you might expect
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
20,185
Laughlin, NV
Sad part is less than 5 ppm FC for your CYA is too low to be safe. But that is up to you.

You will lose about 50% of your FC level each day. Approximately.
 

Rogers877

New member
Jun 15, 2019
4
Florida
Thanks!!! Based on that info My cya level may also Be higher than 70. I’m using a pentair cya test kit which is hard to read between 60 and 100 ppm

My new test kit will take a few days to get here so hopefully the math gets more accurate for me. Thanks all for your advice