Chlorine Generator Salt Discrepancy.

[lucasaltic]

Hey all. I just installed a new AquaTrol HP on my Rental pool. Added 6 bags of salt on startup and tested with a calibrated salinity meter after 24 hours. Tested at 2,570 ppm even though PoolMath said 6 bags should put it just under 3,000 ppm. The cell read 2,500 ppm. Checked the Home pool. Cell testing at 3100 ppm. Salinity meter testing at 3110. PRETTY DARNED CLOSE! So, I’m believing the salinity meter at this point and I concluded that I must have calculated my Rental pool volume incorrectly (it’s an odd-shaped pool with angled geometry). Was operating on the assumption that it was a 12,000 gal pool. Back-calculating the volume based on the salt PPM increase, it must be 16,000 gallons give or take 500 gallons. So I update PoolMath to be 16k gal and add another bag which pool math says should bring it to 2,800 ppm. Test after 24 hours and my meter gives me 2,850. Dead nuts! So I believe the meter even more now. BUT… the cell is only showing 2,600 after 24 hours+ of mixing and is giving me a check salt light. Still generating but low enough for it to worry.

Now, I’m getting a lot of air into my pool circulation loop somewhere. I can see that the pump strainer isn’t full and bubbles come out of the jets even when the chlorinator is off. Haven’t had time to do a proper troubleshooting. My question after saying all of that is: can entrained air throw off the cell reading? Should I address this first or can I ignore this variable for the purposes of troubleshooting my cell? My other question is, should I add more salt to get to the minimum recommended salt level of 2,800 as read by the cell even though my meter(which I trust) reads 2850?

Thanks for any insight you can give.

Luc

 

[HermanTX]

My other question is, should I add more salt to get to the minimum recommended salt level of 2,800 as read by the cell even though my meter(which I trust) reads 2850?

You have to have the salt level that activates the SWCG. The sensors in SWCG’s vary by type but most are based on a conductivity calculation. Some SWCG’s even give a +/-500ppm in their manuals - so you just need to add salt in sufficient quantity to activiate the SWCG but use your value from your salt tester in pool math app to calculate CSI.

Also, the SWCG is only calculating salt value at a instant when flow going through the cell which can vary In salt content. So 24 hrs may not have been enough time for all to mix.

 

[lucasaltic]

You have to have the salt level that activates the SWCG. The sensors in SWCG’s vary by type but most are based on a conductivity calculation. Some SWCG’s even give a +/-500ppm in their manuals - so you just need to add salt in sufficient quantity to activiate the SWCG but use your value from your salt tester in pool math app to calculate CSI.

Also, the SWCG is only calculating salt value at a instant when flow going through the cell which can vary In salt content. So 24 hrs may not have been enough time for all to mix.

Thanks for the response. The cell is activated. The generating light is on and it’s maintaining chlorine. I believe the cutoff salt level is 2300 ppm and it’s showing 2600 ppm. But the low salt warning is flashing. According to the manual, that should go off at 2700 ppm.

 

[ajw22]

Hayward systems do not have any salinity sensor. The salt ppm on the display is a guess based on a perfect cells volts and amps. Just get the salt level in the range that gets the cell to generate.

For more about how your Aquatrol works read Hayward Aquarite SWG - Further Reading

Hayward AquaTrol SWG - Further Reading

www.troublefreepool.com

Get a K-1766 Salt Test kit. Your electronic meter will eventually lead you astray.

 

[lucasaltic]

Hayward systems do not have any salinity sensor. The salt ppm on the display is a guess based on a perfect cells volts and amps. Just get the salt level in the range that gets the cell to generate.

For more about how your Aquatrol works read Hayward Aquarite SWG - Further Reading

Hayward AquaTrol SWG - Further Reading

www.troublefreepool.com

Get a K-1766 Salt Test kit. Your electronic meter will eventually lead you astray.

Thanks for the reply. Actually, I have the K-1776 kit. It’s the one that actually led me astray. I have another thread about it. It was giving me 3,600 salt readings in my Home pool but my cell was showing 2,600 and cutting out. I almost replaced the cell but got the meter and a pool store test first. The cell, meter, and pool store all agreed to within 200 ppm. Added two bags of salt and it went to 3,100 ppm with cell reading the same. Haven’t had any issues since.

That said, I had asked if air bubbles getting into the circulation line can cause the cell to throw errors or read incorrectly. Any thoughts on that?

 

[ajw22]

The cell, meter, and pool store all agreed to within 200 ppm. Added two bags of salt and it went to 3,100 ppm with cell reading the same. Haven’t had any issues since.

The cell, meter, and pool store are all approximations and not actual measurements. The K-1766 gives you the actual salinity.

With a Hayward cell you give it whatever salt makes the cell happy as long as the amps stay under 7.

That said, I had asked if air bubbles getting into the circulation line can cause the cell to throw errors or read incorrectly. Any thoughts on that?

You have an Aquatrol RJ or HP?

What is the orientation of the hump?

Post pics of the cell installed.

 

[lucasaltic]

The cell, meter, and pool store are all approximations and not actual measurements. The K-1766 gives you the actual salinity.

With a Hayward cell you give it whatever salt makes the cell happy as long as the amps stay under 7.



You have an Aquatrol RJ or HP?

What is the orientation of the hump?

Post pics of the cell installed.

Dang it! I was just there but don’t see this and didn’t think to take a pic. It’s a HP. I have a “before” pic which I’ve redlined with the way I installed it (per manual). In direction of flow I have Union, salt cell, Union, flow switch, Union. Cell is right side up with the cord coming off of the top right of the cell as viewed.

 

[ajw22]

Turn the hump down.

How many gallons in your pool?

What type of pool is it?

What size T cell do you have?

Why did you get an Aquatrol and not an Aquarite controller?

 

[lucasaltic]

Turn the hump down.

I had it running at the minimum speed. I did just turn it up today though…

How many gallons in your pool?

Originally thought it was 12k but based on the amount 6 bags increases it, I backed into a calculation of 16,000 gal (see first post in this thread).

What type of pool is it?

See signature. It’s the Rental pool. Sig says chlorine still but just converted to SWCG.

What size T cell do you have?

T-CELL-5. It’s generating plenty of chlorine. I’m just getting the low salt warning. It’s not preventing the cell from generating chlorine.

Why did you get an Aquatrol and not an Aquarite controller?

Because it’s significantly cheaper and I’m cheap. Based on a lot of reading on this forum, several members said it should work just fine. I am aware of the advice to go twoce the pool size rating. This T-CELL-5 says it’s good for 20k gallon so I could go 10k. I know I’m breaking that advice a little bit I have a variable speed pump which I run at low speed for 13 hours per day so I think the rating is good. I currently have the cell set to 30% and it’s been maintaining chlorine levels for 5 days (I’ve actually had to gradually lower it because it was over-producing). Also I don’t think this would have anything to do with the lower salt reading and warning lights I’m getting.

 

[Saturn94]

That said, I had asked if air bubbles getting into the circulation line can cause the cell to throw errors or read incorrectly. Any thoughts on that?

It’s my understanding that air trapped in the salt cell can affect the SWCG salt reading (lower than actual). With a variable speed pump, the current Hayward manual shows the salt cell installed vertically or hump down if horizontal.

PS - I had a similar experience as yours with the K1766 salt test.

 

[Bperry]

I had it running at the minimum speed. I did just turn it up today though…



Originally thought it was 12k but based on the amount 6 bags increases it, I backed into a calculation of 16,000 gal (see first post in this thread).



See signature. It’s the Rental pool. Sig says chlorine still but just converted to SWCG.



T-CELL-5. It’s generating plenty of chlorine. I’m just getting the low salt warning. It’s not preventing the cell from generating chlorine.


Because it’s significantly cheaper and I’m cheap. Based on a lot of reading on this forum, several members said it should work just fine. I am aware of the advice to go twoce the pool size rating. This T-CELL-5 says it’s good for 20k gallon so I could go 10k. I know I’m breaking that advice a little bit I have a variable speed pump which I run at low speed for 13 hours per day so I think the rating is good. I currently have the cell set to 30% and it’s been maintaining chlorine levels for 5 days (I’ve actually had to gradually lower it because it was over-producing). Also I don’t think this would have anything to do with the lower salt reading and warning lights I’m getting.

Rotate the cell so the hump is on the bottom and the air won’t get trapped in there.

 

[ajw22]

I had it running at the minimum speed. I did just turn it up today though…

Turn the hump on the cell down.

T-CELL-5. It’s generating plenty of chlorine. I’m just getting the low salt warning. It’s not preventing the cell from generating chlorine.

You are at close to the lowest sun angle, which occurs on December 21, and the lowest chlorine demand.

I doubt your cell will be adequate in the FL summer. You will probably need to run the cell at 100% close to 24/7.

Do you have the Aquatrol timer turning the cell off when your VS pump is not running?

 

[lucasaltic]

Turn the hump on the cell down.



You are at close to the lowest sun angle, which occurs on December 21, and the lowest chlorine demand.

I doubt your cell will be adequate in the FL summer. You will probably need to run the cell at 100% close to 24/7.

I have a remedy for that. I have a T-CELL-15 on Home pool which is only a 9,900 gallon pool. So I’ll switch the Home pool with the Rental pool cell (by doing the jumper trick) if the T-CELL-5 gets overwhelmed come summer.

Do you have the Aquatrol timer turning the cell off when your VS pump is not running?

I do now (cell turns on 15 minutes after the pump timer comes on and turns off 15 minutes before it turns off) but for the past 3 days I’ve had it running continuously to give everything a chance to mix and give the cell a chance to stabilize. Everything has been stable for the past two days though. No changes in salt measurement on either the probe or the cell in at least 48 hours. Just added another bag of salt about 4 hours ago. Will see if that improved things tomorrow.