Saltwater Pool will not maintain CL

[charbaugh]

I'll start by saying I was lazy during the winter and didn't keep up with the pool, so a lot needed to be done for swim season. I have a 20K gallon salt pool (this is our 12th year, I think) that I am unable to get a Cl reading when testing. Things I've identified/tried/etc:

1. Cleaned the filter (DE)
2. CYA was almost non-existent. I added stabilizer until my CYA now steadily reads about 40ppm.
3. Cleaned salt cell. While it wasn't terrible, I went ahead and cleaned the cell (3/4 water, 1/4 acid).
4. Ensured salt reading is at 3500
5. I have the Pentair IntelliChlor, so ran it in diagnostic mode. It showed no errors and that it is only 20% used.
6. Keeping Ph in check (hard to do here; we naturally run very high)
7. Typically, my IntelliChlor is set to about 40% chlorination. I bumped it to 60% with no change.
8. I placed a couple of Cl tabs in the skimmer to help narrow down if it is a water problem or equipment problem. No noticeable change in 48 hours.
9. Today I pushed the chlorinator up to 100%, just to see if there is any change, but I'm not anticipating one.

My guess is something with the water, but not sure what. Current readings are below. I know that Ca a bit high, but that is in line with what our water typically has run. I'm using a Taylor kit to run the tests.

• Ph = 7.4
• Alk = 60
• CYA = 40
• Cl = effectively 0
• Salinity = 3500
• Calcium hardness = 325
• Saturation Index = -.15

 

[Jimrahbe]

C,

We recommend that saltwater pools have a CYA of 60 to 70

I see you have been a member since 2017.. So, have you done an Overnight Chlorine Loss Test (OCLT)?

Overnight Chlorine Loss Test

If your IntelliChlor's "Cell" light is working, then the cell is making chlorine.

Set the output to 50% and watch the Cell light. It should be on for about 2.5 minutes, while the cell is making chlorine and then off for about 2.5 minutes while the cell is resting..

What FC level are you trying to maintain?

Thanks,

Jim R.

 

[charbaugh]

C,

We recommend that saltwater pools have a CYA of 60 to 70

I see you have been a member since 2017.. So, have you done an Overnight Chlorine Loss Test (OCLT)?

Overnight Chlorine Loss Test

If your IntelliChlor's "Cell" light is working, then the cell is making chlorine.

Set the output to 50% and watch the Cell light. It should be on for about 2.5 minutes, while the cell is making chlorine and then off for about 2.5 minutes while the cell is resting..

What FC level are you trying to maintain?

Thanks,

Jim R.

Thanks for the quick reply. I was not aware of the OCLT, but will take a look and do that. The original pool builder told me 35ish on the CYA, but I can easily raise it to 60. I'm shooting for FC of 3.0-4.0 (again, based on original pool builder info)

 

[Jimrahbe]

C,

Please do NOT increase your CYA until you figure out what is consuming your FC... If you have an algae bloom, even if you can't see it yet, you want to have low CYA.. to kill the algae.

Just to be clear, the OCLT is run with the SWCG off.. Basically need to use Liquid Chlorine to get your FC up to 6 or more ppm, right at sundown. Then you test in the morning just before sunrise and in theory it should still be 5 or 6.. If not, the only thing that will consume your FC at night is algae.

Tell me how the Cell light test goes..

Thanks,

Jim R.

 

[chiefwej]

A saltwater chlorine generator is designed to maintain chlorine levels. Go buy some liquid chlorine to raise your level, then use the SWG to maintain the chlorine level. SWG produces chlorine at a low rate, you should never have it start from zero. Balance the pool first, then turn on the SWG.

 

[charbaugh]

C,

Please do NOT increase your CYA until you figure out what is consuming your FC... If you have an algae bloom, even if you can't see it yet, you want to have low CYA.. to kill the algae.

Just to be clear, the OCLT is run with the SWCG off.. Basically need to use Liquid Chlorine to get your FC up to 6 or more ppm, right at sundown. Then you test in the morning just before sunrise and in theory it should still be 5 or 6.. If not, the only thing that will consume your FC at night is algae.

Tell me how the Cell light test goes..

Thanks,

Jim R.

Just to give an update. The Cell light turns on and off every couple of minutes as you said. I ran the OCLT last night and lost about 2ppm. After your first reply, I went and read all the articles on the OCLT, SLAM, etc., so I guess I have an algae problem that I need to address. Thanks for pointing me in the right direction.

 

[charbaugh]

C,

Please do NOT increase your CYA until you figure out what is consuming your FC... If you have an algae bloom, even if you can't see it yet, you want to have low CYA.. to kill the algae.

Just to be clear, the OCLT is run with the SWCG off.. Basically need to use Liquid Chlorine to get your FC up to 6 or more ppm, right at sundown. Then you test in the morning just before sunrise and in theory it should still be 5 or 6.. If not, the only thing that will consume your FC at night is algae.

Tell me how the Cell light test goes..

Thanks,

Jim R.

New related question. I've been using the Taylor K2005 kit for my testing. Knowing that I'm going into a SLAM I picked up the Taylor K1515 FAS-DPD test. The 2005 shows my FC at 1.5 - 2 (after a moderate dose of liquid chlorine; about 96oz. ). The 1515 show 20. So, could I have bad reagent in ine of the kits, and if so how do I determine which, without a 3rd test kit?

On a side note - while brushing the pool today, I noticed a brownish residue on surfaces where the robot doesn't hit. Guessing that's mustard algae starting, so the SLAM is still warranted. Just need to narrow down the Ch test.

 

[AUSpool]

Check your reagent dates in both kits. The DPD test from the K2005 kit can be subjective, once you’re over its limit there is no way of knowing how far over you are. I would only use that test to establish a basic yes or no to the presence of FC. The FAS/DPD test in the K1515 is much better. If the reagents are within date I would trust that test. You can use a 10ml sample to save on reagents. A test tolerance of 0.5ppm is fine.

 

[charbaugh]

Check your reagent dates in both kits. The DPD test from the K2005 kit can be subjective, once you’re over its limit there is no way of knowing how far over you are. I would only use that test to establish a basic yes or no to the presence of FC. The FAS/DPD test in the K1515 is much better. If the reagents are within date I would trust that test. You can use a 10ml sample to save on reagents. A test tolerance of 0.5ppm is fine.

Doh! Expired reagents in the 2005.

 

[AUSpool]

Doh! Expired reagents in the 2005.

That will do it. Defiantly go thigh the K1515 results. I would think about a new kit or reagents.

The CyA reagent is very stable. The dyes tend to go off the quickest.

I cant remember what to look for to check if the dyes are still ok.

Edit: Ohhh, 2005! I would get a new kit.

 

[charbaugh]

That will do it. Defiantly go thigh the K1515 results. I would think about a new kit or reagents.

The CyA reagent is very stable. The dyes tend to go off the quickest.

I cant remember what to look for to check if the dyes are still ok.

Edit: Ohhh, 2005! I would get a new kit.

Most of the reagents have been refreshed multiple times over the years. Just went through and dbl checked. Only the chlorine reagents were expired. Rest are good for another year.