Salt Cell won't produce enough Chlorine

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Geophffrey

Geophffrey

Well-known member
Feb 22, 2022
106
Austin, TX
Pool Size
18500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-20
Hi All,

A few months ago I switched from liquid chlorine to an Intellichlor IC20 SWG. My pool is 18,500 gallons and was built about a year ago. My pool chemistry is:

FC: 1.5 ppm
PH: 7.6
Total Alkalinity: 91 ppm
Calcium Hardness: 271 ppm
CYA: 65 ppm
Salt: 3,656 ppm

For some reason, I'm still having to add liquid chlorine weekly to keep my FC up. Currently its at 1.5 ppm, which I think is low.

I'm also dumping muriatic acid in constantly.... Does this ever stop?! :)

I'm running my pump 10 hours a day with the salt cell on max output. My rpm is 2,400.

Do you know what I might be doing wrong?

Thank you ahead of time for your help as always!

Jeff
 
Your SWCG is undersized.
To add 4 ppm FC to your pool each day, you need to run the pump 24 hours per day at 90%. Start there and see if the FC stabilizes in your target range. Add liquid chlorine first to get to your target range.

The tests you show above do not look like they come from a proper test kit. How are you testing your pool water chemistry?
 
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Jeff, if the FC continues to fall after following Marty's recommendation, I would do an Overnight Chlorine Loss Test. I don't need to tell you it's crazy hot in our areas right now and only getting hotter. An FC as low as you are showing may already have started a bad brew of organics.

For what it's worth, in this heat my CYA must be at least 70. Anything less doesn't protect my FC enough. So if you think you need CYA, it may help But be sure to pass an Overnight Chlorine Loss Test BEFORE adding stabilizer.
 
Jeff,

As Marty points out, a salt cell should be at least 2 x the volume of your pool.. Who told you an IC20 would work for you??

The only good news is that you have a VS pump. I assume an IntelliFlo, for your main pool pump. This means you can run it 24/7 for not much electrical costs. I suggest you run it as slow as you can and still keep the SWCG flow light green, plus 100 RPM, just to makes sure.

Thanks,

Jim R.
 
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Texas Splash said:
Jeff, if the FC continues to fall after following Marty's recommendation, I would do an Overnight Chlorine Loss Test. I don't need to tell you it's crazy hot in our areas right now and only getting hotter. An FC as low as you are showing may already have started a bad brew of organics.

For what it's worth, in this heat my CYA must be at least 70. Anything less doesn't protect my FC enough. So if you think you need CYA, it may help But be sure to pass an Overnight Chlorine Loss Test BEFORE adding stabilizer.
Click to expand...
Yes, I recently drained a lot of water to bring my CYA down, but I think with the heat in Texas right now, this is obviously an issue. I may add more CYA. I'll try running the pump for 24 hrs a day first to see how that goes. Thanks buddy.
 
Jimrahbe said:
Jeff,

As Marty points out, a salt cell should be at least 2 x the volume of your pool.. Who told you an IC20 would work for you??

The only good news is that you have a VS pump. I assume an IntelliFlo, for your main pool pump. This means you can run it 24/7 for not much electrical costs. I suggest you run it as slow as you can and still keep the SWCG flow light green, plus 100 RPM, just to makes sure.

Thanks,

Jim R.
Click to expand...
When I was researching salt cells, it appeared that the IC20 was enough based on Pentair's suggestions, but upon reading on TFP, I see that most people get a cell that is double what Pentair recommends. Sucks as I just paid for it and installed it. :)

I'll try this. Do you know what RPM I should start at when testing this? Would 1,000 suffice? Thank you Jim!
 
mknauss said:
Your SWCG is undersized.
To add 4 ppm FC to your pool each day, you need to run the pump 24 hours per day at 90%. Start there and see if the FC stabilizes in your target range. Add liquid chlorine first to get to your target range.

The tests you show above do not look like they come from a proper test kit. How are you testing your pool water chemistry?
Click to expand...
Thanks Marty. I use a Taylor kit and confirm with Leslie's as needed.
 
Geophffrey said:
Do you know what RPM I should start at when testing this? Would 1,000 suffice?
Click to expand...
Jeff,

I doubt it, because you have a heater, but it really depends on your pump and your plumbing.

I'd start at a 1000 RPM and expect the flow light to be red.
Then I'd jump up to 1500 and see what happens. If still red jump up to 2000..
Once it turns green you can slowly adjust it up and down and fine tune it.

You want to add about 100 RPM so that as the filter gets dirty the SWCG will still work, unless the filter gets really dirty.

Thanks,

Jim R.
 
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Jimrahbe said:
Jeff,

I doubt it, because you have a heater, but it really depends on your pump and your plumbing.

I'd start at a 1000 RPM and expect the flow light to be red.
Then I'd jump up to 1500 and see what happens. If still red jump up to 2000..
Once it turns green you can slowly adjust it up and down and fine tune it.

You want to add about 100 RPM so that as the filter gets dirty the SWCG will still work, unless the filter gets really dirty.

Thanks,

Jim R.
Click to expand...
Thank you Jim. I really appreciate your help. I’ll try this and if it doesn’t work I’ll look into an IC40 salt cell.
 
Geophffrey said:
Taylor K2005 High Range Swimming Pool
Click to expand...
You will need to supplement that kit with the K-1515 FAS/DPD. To confidently manage your pool free chlorine level you need the FAS/DPD test. It is accurate up to free chlorine (FC) 50 ppm. The K-2005 uses a comparator OTO chlorine test which can only test up to 5 ppm.
 
Geophffrey said:
Taylor K2005 High Range Swimming Pool Total and Free Chlorine Bromine Alkalinity Calcium Hardness Base and Acid Demand pH DP Test Kit Amazon.com
Click to expand...
Add that to your signature - just put Taylor k2005
That kit has a limitation of only testing up to 5ppm fc accurately - most pools with any cya need to test higher than that on a regular basis.
We recommend that you add the fas/dpd kit that accurately tests up to 50ppm

Pool Test Kits - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
an1vrsy said:
You will need to supplement that kit with the K-1515 FAS/DPD. To confidently manage your pool free chlorine level you need the FAS/DPD test. It is accurate up to free chlorine (FC) 50 ppm. The K-2005 uses a comparator OTO chlorine test which can only test up to 5 ppm.
Click to expand...
Great thank you for the info!
 
Mdragger88 said:
Add that to your signature - just put Taylor k2005
That kit has a limitation of only testing up to 5ppm fc accurately - most pools with any cya need to test higher than that on a regular basis.
We recommend that you add the fas/dpd kit that accurately tests up to 50ppm

Pool Test Kits - Further Reading

www.troublefreepool.com www.troublefreepool.com
Click to expand...
Thank you for the reply. If my CYA is ~60 ppm, what’s a good ballpark for my chlorine? I don’t plan on adding any CYA.
 
Jimrahbe said:
Jeff,

I doubt it, because you have a heater, but it really depends on your pump and your plumbing.

I'd start at a 1000 RPM and expect the flow light to be red.
Then I'd jump up to 1500 and see what happens. If still red jump up to 2000..
Once it turns green you can slowly adjust it up and down and fine tune it.

You want to add about 100 RPM so that as the filter gets dirty the SWCG will still work, unless the filter gets really dirty.

Thanks,

Jim R.
Click to expand...
Looks like 1,600 was the sweet spot to make the cell green. Thank you Jim. I’ll let you know if I need to up it. I’ve changed the schedule to run for 24 hrs/day.
 
Geophffrey said:
I’ll try this and if it doesn’t work I’ll look into an IC40 salt cell.
Click to expand...
Jeff,

It should work, but you will have to run the cell at 90% or more... The only downside is that it will use up the cell a little faster.

The upside is that the IC40 and IC20 are interchangeable, so once your cell is used up, you can just replace it with the IC40.. (Or 60)..

Thanks,

Jim R.
 
Jimrahbe said:
Jeff,

It should work, but you will have to run the cell at 90% or more... The only downside is that it will use up the cell a little faster.

The upside is that the IC40 and IC20 are interchangeable, so once your cell is used up, you can just replace it with the IC40.. (Or 60)..

Thanks,

Jim R.
Click to expand...
Oh wow that’s great. I just assumed the IC40 was larger. Thank you so much Jim. You’ve helped me so much.
 

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