High free chlorine, salt cell reading low

[jtkaka]

Hi,

I’m a first time pool owner and this is all new to me. I don’t know if the previous owners really took care of the pool. My biggest problem is the Pentair Intellichlor salt cell says the salt is low, but testing with my K-1766 kit says the salt level is 4400 ppm. K-2005 gives me:
Free Cl: 15
pH: 8.0
Total alkalinity: 110
Ca hardness: 140
CYA: ~32 (this is after I added a pound to a 12k gallon pool and waited 2 days to retest)

I’ve been adding quite a lot of muriatic acid since the pH keeps reading as high. I’ve been reading that this could be why the free chlorine is high, and that could possibly be causing the K-1766 to give me a falsely high reading? Also concerned the salt cell might be broken. I just decalcified this for the first time 2 days ago. My next step was to add thiosulfate anhydrous and maybe more salt but I’m kind of guessing at this point. Any help is appreciated. Thank you!

-JT

 

[PoolStored]

Welcome to TFP!!!!

When your FC >10, the pH test is not invalid. Turn the cell off and let FC come back into range. Remember to follow this...Link-->FC/CYA Levels
High FC will affect the pH test, but not the salt test.

If you have a plaster pool, you really want to raise your CH to 250.

How did you decalcify the cell? Was there a lot of scale, or you just did it to do it?

What are you trying to accomplish by adding thiosulfate anhydrous? I would not recommend that.

Recommended Pool Chemicals

Which should I buy? TFP's recommended pool chemicals are cheap, easy, and won't unbalance your pool water.

www.troublefreepool.com

It certainly could be that the cell has an issue.

Can you fill out your signature? The make/model of the cell may change our advice.

Create Your Signature - Further Reading

www.troublefreepool.com

 

[Newdude]

Hey Jtkaka and Welcome !!!


The K2005 doesn't give you actual FC #s. You need to add the K1515 for actual values. (Or you really have a k2006 and misspoke.)

How old is the pool ?

 

[jsygrls]

Just following guys, but I'm about 90 miles south of him and my water in the mid upper 50's my guess he's ever colder than that, our air temps for the past 3-4 weeks have been 30 degrees to 55ish, that cell should not be producing.

 

[jtkaka]

Updated my signature. Pool was installed in 2013. I decalcified the salt cell just to do it, but it did look pretty calcified. Water temperature is 48 degrees. My understanding is the free chlorine should be less than 4.0 ppm so with a level of 15 that was my reasoning to add an thiosulfate. I did mean the K-2005, it has me calculate free chlorine and combined chlorine and subtract them to get the combined chlorine, so I was looking at the free chlorine value.

 

[PoolStored]

My understanding is the free chlorine should be less than 4.0 ppm so with a level of 15 that was my reasoning to add an thiosulfate.

Your CYA is 40, you can't read test result between the lines, it is logarithmic. Always round up to the next 10.
FC should be maintained for your CYA level. Follow the chart here for your target FC level based on CYA. Link-->FC/CYA Levels

I don't see how it could be calcified...with those numbers. With no record of your historical results, we won't know.

I would start to use pool math. It will help you track results, share here and will make recommendations. Use the same login/password as TFP. Turn on Track CSI, Salt, Water Temperature and Combined Chlorine. Get the subscription to save results ($8 PER YEAR!!!) Link-->PoolMath

When you clean your cell...don't use acid, it damages the rare earth metals that make the chlorine, shortening the life of the cell. See how to clean here.

SWG How It Works - Further Reading

www.troublefreepool.com

How old is your K-2005? If it is old, then I'd get one of our recommended kits. Link-->Test Kits Compared
If not old, then get the Taylor K-1515 or the TFTESTKITS FAS/DPD. You need it for accurate FC testing. Link--> FAS/DPD Chlorine Test Kit

 

[reggiehammond]

Updated my signature. Pool was installed in 2013. I decalcified the salt cell just to do it, but it did look pretty calcified. Water temperature is 48 degrees. My understanding is the free chlorine should be less than 4.0 ppm so with a level of 15 that was my reasoning to add an thiosulfate. I did mean the K-2005, it has me calculate free chlorine and combined chlorine and subtract them to get the combined chlorine, so I was looking at the free chlorine value.

FC/CYA Levels
You'd be wise to read up on FC levels and the relationship to CYA. You're on a collision course with your pool in more ways than one.

 

[jtkaka]

I can certainly read up, expanding on what ways I am in a collision course would be helpful. As I said, this is all new to me. I am trying to read as much as I can but I just started learning about pools for the first time this week.

 

[PoolStored]

I am trying to read as much as I can but I just started learning about pools for the first time this week.

That's why we are here...to help!

 

[ajw22]

Where are you reading up?

TFP does not recommend most of what you describe. We do not recommend mixing methods. It will only confuse you. Read Pool School and decide if you want to drink our Kool-Aid and follow TFP methods. It has been successful for hundreds of thousands of members.

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

 

[jtkaka]

Where are you reading up?

So far mostly YouTube videos

 

[Bperry]

I can certainly read up, expanding on what ways I am in a collision course would be helpful. As I said, this is all new to me. I am trying to read as much as I can but I just started learning about pools for the first time this week.

Read up like referenced below. The FC being below 4ppm is a common misconstrued data point. The correct FC needs to be based on the level of CYA that’s in the water. A FC of only 4ppm might not be enough or might be just fine.

 

[Jimrahbe]

JT,

If your water temp is 48 degrees, your salt cell should not be working at all, and should only have a single red 'cold' light.. If the cell is still working, that is a pretty good indication that the thermistor in the cell's flow switch is bad.. This same thermistor, when bad, is also responsible for very inaccurate salt level readings.

The Flow Switch can easily be replaced, but there are 4 wire and 3 wire flow switches... It would be important to know which one you have, before buying a replacement.

Thanks,

Jim R.

 

[ajw22]

So far mostly YouTube videos

There is a quality control process among experts in what is in Pool School and Further Reading that is not in YouTube videos.

I suggest you forget most of what you picked up on YouTube and start over here.

 

[jtkaka]

Jim,

The “cold” light is not on, but the “low salt” light is on, which is what made me think there is something wrong with the device. I will try to look into what flow switch my device has.

 

[Jimrahbe]

I will try to look into what flow switch my device has.

JT,

You can kind of guess based on the year the cell was made, but the only real way to tell is to cut open the cable between the flow switch and the cell itself and count the wires.. The flow switch is inside the plastic cap with the arrow on it.. The cap snaps off and the flow switch is screwed cell itself.




Thanks,

Jim R.