PH no longer rising with a SWG

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M

Martyp78

Bronze Supporter
Apr 6, 2020
7
Houston, texas
Pool Size
40000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Hi,

I've got an Aqualogic SWG system - and have been happily running using the TFP recommendations for pool chemistry levels for a SWG pool for the last 5 years. I've been through 3 generic salt cells in that period - and had one replaced under warranty - and definitely seen the behaviors where a declining salt reading on the cell was i) a failing salt cell or ii) poor flow rate, on different occasions. I've even done the repair of the Aqualogic board where one of the solders had come undone - and got that working again.

What has been going on for the last couple months is a bit different - salt cell readings are good, but what I've noticed is my PH is no longer rising in the pool. It used to be like clockwork - every 2 weeks, half a gallon of muriatic acid in the pool to drop the PH from 7.8 to 7.2, rinse and repeat. Now it seems stuck at 7.2 My free chlorine level is also low - running at 1.5 to 2 - and I've struggled to raise it using the super chlorinate function. I've resorted to tipping in a gallon bleach occasionally - but not enough to make me think the salt cell isn't producing any chlorine at all (l live in Texas and it is summer). In the days before this I was running free chlorine in the 8 to 10 range. CYA is between 60-80.

The particular salt cell I'm using had been cleaned using a muriatic acid solution as per the instructions, so isn't new. Probably about a year old. Its a Calimar.

Is it the obvious thing - i.e. another duff salt cell not producing chlorine - or something else? If I'm buying a new T-15 salt cell any recommendations - I've used optimum pool technologies and Calimar so far.

Thanks in advance to y'all. TFP is awesome.
 
Martyp78 said:
Hi,

I've got an Aqualogic SWG system - and have been happily running using the TFP recommendations for pool chemistry levels for a SWG pool for the last 5 years. I've been through 3 generic salt cells in that period - and had one replaced under warranty - and definitely seen the behaviors where a declining salt reading on the cell was i) a failing salt cell or ii) poor flow rate, on different occasions. I've even done the repair of the Aqualogic board where one of the solders had come undone - and got that working again.

What has been going on for the last couple months is a bit different - salt cell readings are good, but what I've noticed is my PH is no longer rising in the pool. It used to be like clockwork - every 2 weeks, half a gallon of muriatic acid in the pool to drop the PH from 7.8 to 7.2, rinse and repeat. Now it seems stuck at 7.2 My free chlorine level is also low - running at 1.5 to 2 - and I've struggled to raise it using the super chlorinate function. I've resorted to tipping in a gallon bleach occasionally - but not enough to make me think the salt cell isn't producing any chlorine at all (l live in Texas and it is summer). In the days before this I was running free chlorine in the 8 to 10 range. CYA is between 60-80.

The particular salt cell I'm using had been cleaned using a muriatic acid solution as per the instructions, so isn't new. Probably about a year old. Its a Calimar.

Is it the obvious thing - i.e. another duff salt cell not producing chlorine - or something else? If I'm buying a new T-15 salt cell any recommendations - I've used optimum pool technologies and Calimar so far.

Thanks in advance to y'all. TFP is awesome.
Click to expand...
What are all your other test results. As the TA drops down to 60 or so, the pH will stabilize. If the TA is at least 50ppm and the pH starts with a “7”, then its all fine.

The FC is another story. The SWCG cant raise chlorine very fast and so you need to bring it up with the correct level with liquid chlorine and maintain it with the SWCG.

Also note, cleaning the cell with acid reduces its life span. Dont do that anymore unless its caked up with calcium scale (which shouldnt ever happen if you keep the CSI 0.3 to 0.0)
 
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Bperry said:
What are all your other test results. As the TA drops down to 60 or so, the pH will stabilize. If the TA is at least 50ppm and the pH starts with a “7”, then its all fine.

The FC is another story. The SWCG cant raise chlorine very fast and so you need to bring it up with the correct level with liquid chlorine and maintain it with the SWCG.

Also note, cleaning the cell with acid reduces its life span. Dont do that anymore unless its caked up with calcium scale (which shouldnt ever happen if you keep the CSI 0.3 to 0.0)
Click to expand...
Thanks so much for the response. It makes sense - I guess it was the change in PH behavior from what I was used to over the last few years that made me question it. TA was running about 80 for most of the last few years.

I tested again tonight - levels are as follows:

FC 3.0
TA 90
CH 330
Borates 50
PH 7.3
CYA 70
Salt 2900
Water Temp 90f
CSI -0.35

I've tipped another couple gallons bleach in and we'll see how we go over the next few days. Oh and I'll top the CH up a bit as well - that seems to have drifted lower over the last couple months.

Thanks again.
 
mknauss said:
Have you had 50 ppm Borates in the water this entire time?
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It drifts down over the year - I normally put a 55lb bucket in during the spring, which I did this year. I try and aim for 50. If you've got a decent borates test you could recommend - I'd appreciate that. The test strips aren't the easiest to determine between 25 and 50 ppm.
 
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A couple of notes if you go this way.
Use .5mL of the BTB when you initially add it. Helps with the color change. .5ml is marked on the dropper of most BTB.
Take your TA and divide by 10, add 2, then double. Use that many drops of the R-0009. (TA = 60, /10 = 6 +2 = 8 *2 = 16 drops). This ensures TA bottoms out.
Use 3 1/8th teaspoons of the mannitol.

Follow the directions, modified with the above and it is VERY accurate.
 
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