did i go overkill on shock?

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edub370

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May 21, 2015
14
Overland Park, KS
My fiance and i just bought our first house last year. Lucky us, it had a 37,000 gal pool! So this is our first year opening. we were having some issues with algae upon opening. I did some research and decided to go with the TFPC method for maintaining the pool. picked myself up a Taylor K-2006 test kit and decided to go ahead and shock the pool. After some initial test i saw that my numbers were about spot on (cya, pH, etc..). I see that vinyl liner pools require about a 15 ppm to shock. i calculated to be about the right amount of bleach to take me from my initial 2.8 ppm to 15 ppm to kill this stuff dead. an hour later i tested the water about an hour later and realized i had overshot! i ended up with approx 18 ppm after shocking. am i in any danger of damaging my liner by running this high of a PPM for a short time to shock? obviously I'm going to let it lower for a while and not add any more chlorine. but if this chlorine level sits like this for a day or 2, am i in trouble? should I be looking to add a neutralizing chemical asap? or am i just overreacting like a pool newb?

any advice would be great! thanks guys
 
Welcome! :wave:

No, 18 FC is not going to damage anything, provided your CYA is around 40.

For future reference.... you can do the FC test using 10 ml of water. That way each drop is .5 instead of .2. It speeds it up and saves a lot of the R-0871 reagent. Also, Taylor is much like coffee companies. They tell you to use far too much of their product each time. One scoop is usually enough powder. If you have one or two undissolved crystals, that means you have enough. Somehow they dissolve during the test.
 
Welcome to TFP!

Your FC level alone doesn't tell us much without also knowing your CYA level. Depending on your CYA level, 18 could be way to high, just right, or not enough. Where did you see that vinyl liner pools require 15 FC to "shock"?

If you wouldn't mind, could you post your full set of test results?

FC
CC
pH
TA
CH
CYA

Also, if you are following the TFPC method (and it is a great method to follow), you should know we don't serve Shock around these parts. We only keep SLAM on tap. :cheers:
 
Wow, you guys are great! such quick responses! i had seen on e a few other pool forums that people recommended vinyl liner pools be around 15ppm when shocking to avoid possible damage (probably conservative).

full numbers:

FC = 2.4
CC = 2.8 (transposed these in my first post)
pH = 7.6
TA = 100
CH = 230
CYA = 35
 
edub370 said:
Wow, you guys are great! such quick responses! i had seen on e a few other pool forums that people recommended vinyl liner pools be around 15ppm when shocking to avoid possible damage (probably conservative).

full numbers:

FC = 2.4
CC = 2.8 (transposed these in my first post)
pH = 7.6
TA = 100
CH = 230
CYA = 35
Click to expand...

Use the chart here for you SLAM level http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

- - - Updated - - -

Get your FC back up to SLAM level. The longer it is below SLAM level the longer it will take.
 
edub370 said:
holy cow. just tested again. and within the 3 hours that its been shocked its dropped to around a 5-6 ppm! i didnt even know that was possible! is a 12ppm drop in a 3 hour span normal under heavy algae conditions?
Click to expand...
Yep. And if any CYA converted into ammonia, it'll use up bleach almost as fast as you can pour it in. Your high CC numbers sort of hint at that. The good news is that as things start to die off, the thirst decreases.
 

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next question, when testing with my taylor k-2006 kit, when i start adding droplets to check my FC, i'm supposed to add until the water goes from pink to clear. well i can get the water to go to clear, but when i let the water sit for a minute or 2 without swirling after that, it starts changing back to pink. does that mean i need to add more droplets, or am i just letting it sit around too long? really makes my confidence in what im reading from the kit go down.
 
edub370 said:
haha i guess it could be worse

thanks again for the quick responses. u guys have really helped me out a ton!
Click to expand...

since your FC is dropping so fast, raise your FC above the SLAM level. if your SLAM level is 15ppm, take it to around 20ppm. that way you spend more time at or above 15ppm. if you take it to 15ppm, the levels aren't staying there very long and its gonna take more time to finish. im not saying go to 30, but some extra helps a lot. the idea is to NEVER allow the FC to drop below your SLAM level, only way to do that is constant additions of FC, or raise it higher.

I would take it to 20ppm, as soon as it gets to 15ppm, raise it again to 20ppm. eventually the FC loss slows down and you can bring it a bit lower.
 
DaninFLA said:
im not saying go to 30, but some extra helps a lot. the idea is to NEVER allow the FC to drop below your SLAM level, only way to do that is constant additions of FC, or raise it higher.
Click to expand...

I took it to 30, probably more than 30 for brief moments before the ammonia sucked it dry. My first 5.5lbs of CYA resulted in test results of 0. Once I had every bit of leaf, trace of silt and spec of dust out of the pool I attacked. I brought PH down, got calcium and CYA up and Dumped enough bleach to get up above 30. I waited until after sunset to give my bleach the best chance at surviving. Its working. If my pool wasn't so deep, I think it would look clear to anyone else.
 

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