T-Cell Trouble shooting

[kscongdon]

I have a Hayward T-15 SWG. It's about 2 years old. I suspect it is going bad because the chlorine output is very low or almost nothing. I added a bag of salt a couple of weeks ago. Instant Salt is at 2934 and Average Salt is at 3537. I need to confirm the salt level with a test but haven't done that yet. There was scale on the plates and I acid washed it two days ago, but still the chlorine level of the pool is at about 1ppm despite running the T-Cell at 50% yesterday and SC mode today for 2 hours so far.
I listed the other diagnostic values below. How do I know if the t-Cell needs to be replaced? What do the values in the diagnostics indicate? How do I know what they mean?
I read in another thread that acid washing reduces the life of the t-cell. I've washed it like this maybe 6 times since owning it. Should I clean it another way?

Cell Temp: 78.1
Instant Salt: 2938
Average Salt: 3537
Cell Current: 5.73A
Cell Type: T-Cell-15
Relay Polarity: K2
Cell Voltage: 25.73v

 

[ajw22]

This is the basic information we need to know in diagnosing a problem:

• Report all readings when you..
  • Move the switch from auto to off and check all of the readings.
  • Move the switch back to auto and recheck the readings.
  • Move the switch to off for a minute and then back to auto and recheck the readings.
• What are the first seven characters of the cell and box serial numbers?
• What is the actual salinity and how are you measuring it?

Hayward Aquarite SWG - Further Reading

www.troublefreepool.com

 

[kscongdon]

Hi @ajw22 ,
Thank you for your response. I have an Omnilogic system. When you say move the switch from auto to off, what does that mean in the context of Omnilogic? The diagnostics are not shown when the chlorinator is switched off.
The Omnilogic sent me a message over the weekend that the t-cell needed to be cleaned (about 5 days after I cleaned it). I took it out again just to check for scale that might have formed during that time and it looked fine so I didn't clean it.

Here are the answers I can provide now:

• What are the first seven characters of the cell and box serial numbers?
  • I realize I miss-reported the model number in the original post
  • Model # TCELL940
    Serial # 4E19212
• What is the actual salinity and how are you measuring it?
  • I got a sample tested at my local pool store on Saturday. It showed 3100.
  • I added about 20lbs after that
  • Diagnostics now read
    • Instant Salt: 3253
    • Average Salt: 3672

 

[ajw22]

You need to get your own test kit. A TF100 Test Kits or Taylor k-2006C. Pool Test Kits - Further Reading

Once you get your own test kit post a complete set of test results.

Do a Overnight Chlorine Loss Test

I suspect you have algae in your water which is consuming the generated chlorine.

 

[kscongdon]

I have the TF100 kit. I'll do the overnight test tonight. thank you.
Also, the chlorine levels are higher today, around 5ppm. I've put the SWG at 50% now

 

[ajw22]

What is your daily pump runtime and pool volume?

 

[ajw22]

Also you should get the Taylor K-1766 salt test kit.

We don’t rely on any pool store tests.

 

[kscongdon]

The overnight test did not show a drop in Chlorine. I think the SWG is working properly. I think the problem was unusally low CYA. My CYA test yesterday was only 32ppm even after having added 4lbs last week. I will get the CYA up to optimum level today.
15k gal
pump runs 9am to 9pm daily at low speed usually unless undergoing treatment or pool use.

 

[ajw22]

How do you get a CYA value of 32 with your TF100?

The lines are logarithmic, not linear, and you cannot eyeball values in between the lines. Halfaway in between is not 5. Therefore we round up. If the dot disappears anywhere between 40 and 30 we call it 40.

Your CYA is 40.

Running your Tcell940 at 50% for 12 hours/day in your 15K pool will generate 2.8 ppm/day of FC.

If you were running at less then 50% before it was not making enough daily FC.

 

[kscongdon]

Thank you, I didn't know that about the CYA measurement. I was estimating because it was not quite at the 30 line.