FC over 75

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stevenfmurray

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Feb 7, 2018
28
Goose Creek, SC
Got back from vacation a few days ago. New salt cell and EasyTouch installed a few weeks ago. Finally tested the water this morning and shockingly (no pun intended) my FC is over 75 (I stopped adding the reagent). I'm in the process of starting a partial drain. Any other advice? I'm kind of freaking out as I leave town for another week in 4 days and I want my kids to be able to swim while I'm gone.

Details: I recently upgraded from an IC15 to IC40. I've been running the new cell for 8 hours/day at 50%, but have been out of town, so haven't gotten it fine-tuned yet to match demand. CYA has been around 70-80. Salt was reading low on the cell a few days ago and tested at 2600 yesterday, so just added a bag of salt last night to bring it back up...I should have done a complete test a few days ago I know.
 
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Why are you dumping water? Removing water will reduce your FC and CYA equally, so it's actually not affecting the ratio and not lowering the active FC levels. With that high of FC level the sun will burn it off fast so you can just leave it, or you can buy some chlorine neutralizer from the pool store if you really want to get it down fast.
 
Donldson said:
Why are you dumping water? Removing water will reduce your FC and CYA equally, so it's actually not affecting the ratio and not lowering the active FC levels. With that high of FC level the sun will burn it off fast so you can just leave it, or you can buy some chlorine neutralizer from the pool store if you really want to get it down fast.
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Dumped a few thousand gallons. Refilling now, then plan to add CYA to bring it back up to 75 or so. Any success with the sodium thiosulfate? I've heard nightmares about people overdoing it and then having to dump loads of Cl in. Willing to do it though if it can be controlled.
 
Since you've dumped a good amount of water I would hold off adding any CYA and let the FC come down on it's own. You'll be surprised how fast it comes down with the sun on it and at the lower CYA level.

Sodium Thio works really well, and if you decide to try it, be very conservative in the amount you add. Add a little and wait a while then test and add again if you need to.
 
Sure, some people over do it with thiosulfate, but I have also heard of people accidentally overdoing it with chlorine and I still use the stuff ?

I personally would just let the sun burn it off, but agree with Bama that thiosulfate will work fine if you want to go that route. Use half of what you think you will need and retest after 15-30 minutes. Once you get down to SLAM level you are in the clear. But really the damage (probably minor) is done, a few more hours won't hurt anything and with so much unbound chlorine if you are having a sunny day today you will easily lose half of that chlorine by night fall.
 
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Are you sure that you're doing the test correctly?

Is the pool covered?

When is the last time that you checked the chlorine?

Try making a sample with 1 part pool water and 3 parts distilled water. Mix it up and test it for chlorine and multiply the result by 4.

Try testing the tap water to make sure that the test is working.
 
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Bama Rambler said:
Since you've dumped a good amount of water I would hold off adding any CYA and let the FC come down on it's own. You'll be surprised how fast it comes down with the sun on it and at the lower CYA level.

Sodium Thio works really well, and if you decide to try it, be very conservative in the amount you add. Add a little and wait a while then test and add again if you need to.
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Makes sense. I'm refilling now...should be done in a few hours. I'll retest when it's topped off and update.
 
JamesW said:
Are you sure that you're doing the test correctly?

Is the pool covered?

When is the last time that you checked the chlorine?

Try making a sample with 1 part pool water and 3 parts distilled water. Mix it up and test it for chlorine and multiply the result by 4.

Try testing the tap water to make sure that the test is working.
Click to expand...

Yes, results sound crazy, but I'm sure.

Pool is uncovered.

Last checked probably a few weeks ago. Too long, but I've been out of town. Certainly wasn't ideal to have the new, much more powerful IC installed right before I left, but really no other options.

When the pool is full again, I'll retest. Good ideas about diluting and testing the tap water. I'll do that in a bit.
 
An IC40 at 50% for 8 hours per day will add 2.1 ppm per day. That means it would take 35 days to get to 75 ppm. And that's assuming no chlorine lost to the sun.

It just doesn't add up. There's a mistake in the testing or in the amount of chlorine being added.
 

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JamesW said:
An IC40 at 50% for 8 hours per day will add 2.1 ppm per day. That means it would take 35 days to get to 75 ppm. And that's assuming no chlorine lost to the sun.

It just doesn't add up. There's a mistake in the testing or in the amount of chlorine being added.
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Holy Crud! Wow...I feel like a moron. Thanks for the data that caused me to take another look. With the initial test, I now realize I accidentally added R0003 instead of R0781. No wonder the sample looked so dark red and wasn't getting any lighter!

With 500-10000 gallons left to fill, the current FC is 14.
 
stevenfmurray said:
Holy Crud! Wow...I feel like a moron. Thanks for the data that caused me to take another look. With the initial test, I now realize I accidentally added R0003 instead of R0781. No wonder the sample looked so dark red and wasn't getting any lighter!

With 500-10000 gallons left to fill, the current FC is 14.
Click to expand...
Once I burned through half a bottle of R-0012 before I realized I used R-007 instead of R-0010.

You are not the first nor will you be the last.
 
For a pool with good sun exposure, it would be almost impossible to get to 75 ppm even if you ran at 100% for 24 hours a day.

For example, if the normal fc was 5 and you lost 2 ppm per day and the SWG added 2 ppm per day, the level would stay at 5.

If you cranked up the production to 12 ppm per day, the fc would begin to climb, but the loss would also begin to climb.

At 10 ppm fc, the loss would be 4 ppm. At 20 ppm, the loss would be 8 ppm. And, at 30 ppm fc, the loss would be 12 ppm.

So, you would reach an equilibrium at 30 ppm with a gain of 12 ppm and a loss of 12 ppm per day.

Now, if the pool was covered, the loss rate would be close to zero and you could hit 100 ppm fc in a week.
 
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