First Time I’ve needed to SLAM

[Sharla]

Tests today:
FC: 0
CC: 0
TC: 0
pH: 7.2
TA: 90
CYA: 40
Salt: 2400
Water temp: 50

Water looks fine. I don’t see any problems. I’ve just been really lazy lately about testing the water and maintaining the proper water chemistry. (I know, I know...No need to scold me.)

I added a gallon of 6% bleach and tested again four hours later. FC was still zero. This was a shock to me. I’ve never had to SLAM before.

I used the tools here to determine that I would need to add about 3.5 gallons of 10% liquid chlorine to reach shock level of FC 24. I added it and tested two hours later. FC is 27.5 so I hit the target I was aiming for. Only overshot slightly.

I’ve read the SLAM directions, but I still feel a little unsure about what I’m supposed to do next. Should I test again before bed, or do I wait until morning to see if the level stays the same overnight? What results am I looking for?

Thanks for your help!

P.S.
I also added salt. Didn’t mention it because I’m not worried about that, as it’s easily fixed.

 

[aussieta]

adjust chlorine as often as possible
minimum before bed, in the morning, after work
the more often you test and adjust the quicker it will go
slam is finished when you meet the 3 criteria
water is clear, zero chlorine loss overnight and zero to 0.5cc
Pool School - SLAM - Shock Level And Maintain

 

[Sharla]

Thank you! I think I’m done then. The water was already clear, as far as I could tell, and still looks fine this morning. I didn’t lose FC overnight. My CC is .5

Is it normal that I wouldn’t have to bring it up to shock level more than once? Maybe I just caught things early, FC had just recently reached zero, it’s cold, and there hadn’t been enough time for algae to grow?

The Pool School SLAM instructions say it can’t be done overnight, so I’m hesitant to think this was actually solved overnight.

 

[mknauss]

Just because your FC dropped to zero does not mean you needed to SLAM, especially with cold water temperatures.

It is best to do a Overnight Chlorine Loss Test with FC of 10 ppm or so (based on a normal CYA of 50 or so) prior to initiating a SLAM.

 

[aussieta]

well done you caught it early
a scare helps to remind you to test more frequently

 

[Sharla]

Just because your FC dropped to zero does not mean you needed to SLAM, especially with cold water temperatures.

It is best to do a Overnight Chlorine Loss Test with FC of 10 ppm or so (based on a normal CYA of 50 or so) prior to initiating a SLAM.

Thank you so much for this info. What’s done is done, but I want to understand this better.

I did try adding one gallon of 6% bleach to bring the FC into a normal range. I was working in the yard in the couple hours after adding that gallon and I could smell a chlorine smell coming from the pool, and it has never smelled that way before. When I finished the yard work, I tested the FC to see how much the gallon of bleach had brought up the FC, but it was still zero. That’s why I thought a SLAM was warranted.

Are there any steps you think I should’ve taken between the first gallon of bleach and the decision to SLAM? I would love to know what I should do differently next time.

- - - Updated - - -

well done you caught it early
a scare helps to remind you to test more frequently

Thank you! Yes, I needed that kick in the butt to remind me to test often. My SWG has worked so well that I allowed myself to slip into a “set it and forget it” mindset. Thanks for your help!

 

[mknauss]

The best thing to do is read the SLAM Process article.

Sounds like you had something going on if you smelled the chloramines.

An Overnight Chlorine Loss Test is something that can be done periodically to check.