Rapid calcium buildup in SWG

[kong]

I have recently been experiencing rapid buildup of calcium in my SWG. I can't point to anything that has been happening to the pool that would contribute to this. The change has been radical -- I've gone years between needing to acid wash on this cell and the one prior -- but I had massive buildup upon inspection about a month ago, I acid washed it, and a similarly terrible buildup has returned already.

The cell has been in service 3 years, 9 months.

The chemistry is typically within these ranges (I target a slightly negative CSI at all times):
FC: 3.0 - 5.0
CC: 0
pH: 7.5 - 7.6
TA: 70 -90
CH: 280
CYA: 30 +/- (have trouble keeping CYA in pool)
Salt: 3200
Current water temp: 85

On each occasion of the buildup, I've experienced reduced chlorine output of course, but overall it has been a challenge to keep chlorine in the pool this summer versus other summers.

I'm beginning to suspect that the cell needs replacing, but would like to get a second opinion. Just how does one really know the cell needs replacement?

 

[mknauss]

Welcome to the forum!
What SWCG do you have? Can you add that to your signature. Does it reverse polarity to self clean it?
I know you gave us ranges for tests, but are those weekly pool store tests or from your own test kit?
A positive CSI, especially with elevated TA and pH, will create scale in the SWCG.
I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.

 

[kong]

It's a Hayward T-15 SWG paired to the Hayward automation system. Yes, it reverses polarity every time it starts.

The values are my own from a TF-100 test kit. I sanity check them with a pool store I trust from time to time, and we are in good agreement.

As I said, I seek to maintain a slightly negative CSI at all times, so I don't suspect the pool chemistry. I suspect that calcium buildup that rapid has to come from heat or something else crazy going on.

Like I asked, is there a good way to determine that a SWG is toast?

Edit: the salt level might have helped, too, huh? I target 3200. It's been a little up and a little down due evaporation / rain.

 

[mknauss]

Salt level will not effect the CSI very much. Water temperature does. Be sure you enter current temperature into Poolmath to calculate CSI..

The Hayward SWCG have a diagnostics readout. Run that and post it.

 

[kong]

Here is a current snapshot of the diagnostics readout. The salt is a bit high because the cell was reading artificially low numbers when calcified and I got suckered into adding more salt. This current salt level sanity checks with the Taylor salt test kit.

• +24.85V +6.73A
• 84°F 3400 PPM

 

[mknauss]

@JamesW -- can you take a look at this thread? Seems odd this cell is scaling with the water chemistry parameters reported.

Thanks

 

[JamesW]

Nothing that stands out. Can you list all chemicals that you have added in the last 6 months?

 

[ajw22]

Here is a current snapshot of the diagnostics readout. The salt is a bit high because the cell was reading artificially low numbers when calcified and I got suckered into adding more salt. This current salt level sanity checks with the Taylor salt test kit.

• +24.85V +6.73A
• 84°F 3400 PPM

Check volt and amperage in both polarities. See page 3.

https://images.inyopools.com/cloud/documents/aquarite-troubleshooting-guide.pdf

I suspect the controller is not cycling polarities.

 

[JamesW]

They have AquaLogic, which is different from the Aquarite. To switch polarities, you go to diagnostics and then press the + button.

 

[ajw22]

They have AquaLogic, which is different from the Aquarite. To switch polarities, you go to diagnostics and then press the + button.

Oops. Right idea. Wrong box.

 

[kong]

Thanks guys, I appreciate the feedback.

Nothing that stands out. Can you list all chemicals that you have added in the last 6 months?

Nothing very interesting. We've had a lot of rain so I've added lots of salt to keep up, and I've had a couple of episodes of chlorine demand so I've shocked a couple of times. So going by memory (I don't log this):

120 lbs salt
24 lbs baking soda
6 gallons 10% bleach
acid as needed to keep pH in check

Check volt and amperage in both polarities. See page 3.

https://images.inyopools.com/cloud/documents/aquarite-troubleshooting-guide.pdf

I suspect the controller is not cycling polarities.

The polarity reverses when pressing the + button in diagnostics, and I've observed the polarity reversing in normal operation.

 

[kong]

I wanted to follow up and thank those that took the time to respond and offer suggestions.

A couple of weeks after the last cleaning, and my post, chlorine started disappearing from the pool and the indicated salt levels were dropping (into the high 2000s from 3400). I pulled the salt cell expecting it to be calcified all over again, but it was perfectly clean. From the outset, I suspected the cell was dying but the calcium buildup was really odd. And I didn't know what to make of the lack of calcium this time.

Anyway, I purchased a new cell and it's been running fine for a couple of weeks. There's chlorine in the pool and the salt readings look sane, so I'm happy.

I just wish I had an explanation for all that calcium. After another couple of weeks I'll reinspect this one, but all indications are everything's fine with the new generator.