Lost a Ton of FC After First Salt Pour?

Mavven

Well-known member
Jul 21, 2021
60
NY
Pool Size
18000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Hey all, if you follow my previous post. You will see that I have successfully completed my SLAM (for algae) process yesterday. I don't have a signature up yet. 27'ft round 54" inches deep saltwater 8000. 190sqft cartridge filter, 2HP 2 speed pump, RJ45+ SWG. Pool is 18,000 gallons

So after my SLAM I decided to add five 40 pound bags of salt to get the process of turning salt water for the first time. Started with a salt level of 400ppm measuring with my taylor kit.

Let it run for about 4 hours with pump on high. Retested salt and I'm at 1800ppm which is fine as I ran out of daylight, plus I'd rather go slow to get to the goal of 3,500,-3,800ppm salt.

I tested my FC and it had been at 13ppm in the morning confirming my OCLT was legit and done. To my surprise I was at 3.5 ppm four hours after adding salt. Is that normal? I ended adding more liquid chlorine to bring it up to 7ppm or I think. Still have to check.

I also added 4 pounds of granular CYA yesterday (in a sock) to bring the CYA up to 65. Not sure if the salt or CYA would have cau sed the chlorine loss?
 
Adding a lot of calcium chloride or sodium chloride (Salt) seems to cause a big FC drop in some pools, but it is not clear exactly why.

Maybe something in the mix, but theoretically it should not cause a loss.
 
Neither will cause chlorine loss. Organics and the sun consumes the FC.
It was sunny all day yesterday. I guess it's possible to lose all that chlorine without any in the system or the SWG not up and running yet?
 
Okay, so something is just not making sense. Just went out to test. 0.5ppm FC What the heck?

My CYA is between 45-50 did the sock method yesterday. I know it can take more then 24 hours to completely register. So I'm fine with that.

Salt is still at 1800 ppm from last night's 5 bags added. Pool is crystal clear. Not understanding the extreme FC loss. Just added a gallon of 12.5% liquid chlorine to bring it to 7ppm FC

I know I passed the OCLT because I did it 2 nights in a row just to be safe. Both nights had zero ppm loss..

I put in the diamond crystal salt from home depot, that most people here have used. It has to be the salt messing something up.

Gonna check my PH and TA now.
 

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It happens, but we don't know why.

Not much you can do other than rebalance.
Okay, thanks James. Appreciate the response. I know someone above commented, neither will cause chlorine loss. That's why I'm I inquiring more. That comment had me a bit nervous.

If this xan sometimes happen, then I feel comfortable adding liquid chlorine until I get the salt within range and able to power up the RJ45+
 
Given that it dropped below or close to 0.5 I’d suggest after rebalancing you check overnight chlorine loss again.

EDIT: To clarify, if it is a containment or not chlorine went low enough that you should check; not doubting earlier tests.
 
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I’ve experienced the FC crash after adding calcium chloride multiple times, and I didn’t add a lot. Never noticed it after adding salt but don’t add salt very often and never more than maybe 15 lbs at a time.
 
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