Why does Pool Technician set Aqua Rite to t-9 instead of t-15?

Drew S

Member
May 27, 2020
7
Georgia
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I am trying to understand why the Pool Tech has the Aqua Rite set to t-9 for the Aqua Rite 940 cell. I believe it should be set to t-15 but he suggested that I leave it at t-9. My concern is that I believe the t-9 setting limits the voltage applied and therefore only produces 0.98 Lbs chlorine compared to 1.47 Lb when set to t-15. Any ideas?
 
With a 400K BTU Natural Gas heater, the amperage can exceed 8 amps at normal salinity.

For example, if the water temperature is 86 degrees and the heater is on, then the water exiting the heater will be about 102 degrees, which makes the cell amperage go way up.

Watch the cell temperature and amperage with the heater off and with the heater on.

If the amperage gets anywhere near 8.0, you are at risk of a high amp/high salt error.

With the Setting on T-9, you can keep the salinity lower and avoid a high amp shutdown.

I would use the T-9 setting.
 
Last edited:
My concern is that I believe the t-9 setting limits the voltage applied and therefore only produces 0.98 Lbs chlorine compared to 1.47 Lb when set to t-15.
The voltage is the same either way.

At 8.0 amps, the unit will shut down.

Using the T-9 setting, allows you to keep the salinity lower without triggering a low salt warning because the T-9 setting makes the salinity read about 1.5 times higher than actual.

So, an actual salinity of 2,700 ppm will read about 4,000 ppm on a T-9 setting.

An actual salinity of 2,400 ppm will read about 3,600 ppm on a T-9 setting.

Keeping the salinity between 2,400 ppm and 2,700 ppm (actual) keeps the amperage below 8.0 when the heater is on.

What is your water temperature and what temp is the heater set to?
 
Last edited:
With a 400K BTU Natural Gas heater, the amperage can exceed 8 amps at normal salinity.

For example, if the water temperature is 86 degrees and the heater is on, then the water exiting the heater will be about 102 degrees, which makes the cell amperage go way up.

Watch the cell temperature and amperage with the heater off and with the heater on.

If the amperage gets anywhere near 8.0, you are at risk of a high amp/high salt error.

With the Setting on T-9, you can keep the salinity lower and avoid a high amp shutdown.

I would use the T-9 setting.
Pool water is 87 F today. The heater is off for the summer season.
 
If the amps are below 8.0, you can use a T-15 setting.

If you use a T-9 setting, you can keep the salinity lower if you want.

Either way is fine.

I would use a T-9 setting.
 
Thank you for the detail. I will leave at t-9. The Aqua Rite shows 3200 average salinity and 3100 instantaneous.
That puts the actual salinity at about 2,100 ppm.

You can increase the salinity some to improve cell performance, just keep the amperage well below 8.0 especially if you are going to use the heater.

Track the actual salinity with a K-1766 salt test kit.

 
Using Taylor K-2006 Salt test gives a persistent brick salmon color at 17 drops x 200 ppm = 3400 ppm. Your comment that the salt is 2100 ppm is making me wonder what the actual NaCl is in the pool.
 
To get the performance of the cell, divide the instant salinity by the actual salinity.

If the ratio is less than 75%, it's time for a new cell.

For example, 2,000 (instant salinity) ÷ 3,600 (measured salinity with a test kit)=56%.

Check the cell and clean it if necessary.

If that doesn't work, it's time for a new cell.
 

Enjoying this content?

Support TFP with a donation.

Give Support
How old is the cell?

Can you show the cell labels?

Maybe the cell is dying and reporting low salt.
IMG_2565.jpeg
Reading the serial number I believe the cell was made in 2017. It is generating chlorine and pool tech recently inspected.
 

Attachments

  • IMG_2564.jpeg
    IMG_2564.jpeg
    276.5 KB · Views: 3
 
James - thank you for taking time to answer my questions.

This morning the Taylor salt test shows 3200 ppm and Aqua Rite average shows 3100 ppm. I understand the cell is likely near end of life. Is it suggested that both the cell and control box be replaced or just the cell?
 
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.