Stumped by SWG

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T

Turniptruck

Active member
Aug 17, 2023
44
Macungie, PA
Pool Size
28000
Surface
Vinyl
Chlorine
Salt Water Generator
Greetings,

I have a 28K gallon inground vinyl liner pool. Since I filled the pool for the first time last summer, I have not been able to produce enough chlorine to keep up. The salt system is an Excel 60K gallon rated system. (I've been using CalHypo to maintain sanitizer level)

I am confident the problem is not high chlorine demand due to algae, etc. Using a Taylor FAS-DPD titration test with 25ml/2 PPM per drop, my overnight loss was .2 PPM. Current readings at end of day today are:

pH 7.5
FC 3.8
CC .4
TA 80
CYA 65
Salt 3700
Water Temp 74°F

I am running the chlorine generator at 100% for 12 hours per day. The voltage supplied to and the current drawn by the cell indicate normal operation at approx 25 volts and 5.3 amps. Just to be sure, I measured the voltage and current with my own meter and the readings match what the cell controller is telling me. I'm quite confient that the electrical conditions at the cell are normal.

Could a faulty cell still draw normal current but produce insufficient chlorine?

I'm very stumped by this.

Thank you.
 
Turniptruck said:
Greetings,

I have a 28K gallon inground vinyl liner pool. Since I filled the pool for the first time last summer, I have not been able to produce enough chlorine to keep up. The salt system is an Excel 60K gallon rated system. (I've been using CalHypo to maintain sanitizer level)

I am confident the problem is not high chlorine demand due to algae, etc. Using a Taylor FAS-DPD titration test with 25ml/2 PPM per drop, my overnight loss was .2 PPM. Current readings at end of day today are:

pH 7.5
FC 3.8
CC .4
TA 80
CYA 65
Salt 3700
Water Temp 74°F

I am running the chlorine generator at 100% for 12 hours per day. The voltage supplied to and the current drawn by the cell indicate normal operation at approx 25 volts and 5.3 amps. Just to be sure, I measured the voltage and current with my own meter and the readings match what the cell controller is telling me. I'm quite confient that the electrical conditions at the cell are normal.

Could a faulty cell still draw normal current but produce insufficient chlorine?

I'm very stumped by this.

Thank you.
Click to expand...

Since you passed an OCLT, you could try an Overnight Chlorine Gain Test (run the swcg at 100% from sunset to sunrise) to see how much chlorine is being generated.
 
If it is a 60K cell 12 hours at 100% should be making about 4.5ppm of FC each day for your pool.

Get the voltage and amp readings for both sides of the cell. While it is on, read the numbers and then turn off the SWG switch and turn it back on. The 2nd side should be active and compare those readings. I have always had one side of the cell give out first while the other side will still produce chlorine.

Does this system show the instant salinity reading or just the average and how close are they to the actual salinity?

How much sunlight is on the pool?
 
Both sides of the cell are in parallel on the PCB of the controller. The controller cannot run just one side. Both sides of the cell show a similar resistance when measured, indicating to me that one is not faulty.

At 100% the controller supplies 25 volts and the cell draws 5.3 amps. This is normal according to the manufacturer.
ping said:
If it is a 60K cell 12 hours at 100% should be making about 4.5ppm of FC each day for your pool.
Click to expand...
That would be wonderful. Using CalHypo, I go through approx 2 PPM per day when the solar cover is left off.
ping said:
How much sunlight is on the pool?
Click to expand...
11am through sunset. Solar cover is left on some days.
 
If the amps and voltage are in normal parameters then it should be producing chlorine.

How old is the cell? The chlorine production rate will drop some with age.

Is the pump changing speeds during the run time? If too low of flow it might be turning the SWG off and you don't realize it.

Try Saturn94's response in #2 reply.
 

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Turniptruck said:
That would be wonderful. Using CalHypo, I go through approx 2 PPM per day when the solar cover is left off.

11am through sunset. Solar cover is left on some days.
Click to expand...
I'm amazed you're only losing 2ppm a day, with a CYA of 65.

I know my pool loses close to 4 right now, and my CYA is 80. I haven't done a OCLT since opening, but I only lost 9ppm from November through April, which is a lot less than 1ppm overnight ;)
 
Have you tried the overnight chlorine gain test suggested earlier? Instead of depending on calculations, you can do a real drop based test to determine the amount of chlorine your SWG is making.
 
Turniptruck said:
I could do that. However, all calculations of chlorine generation inducate that I should be able to make more than enough during my current 12 hour run cycle.
Click to expand...

Your pool uses what your pool uses. Sometimes it needs more chlorine than other times. You need to increase the percent or increase the runtime at least until you find out what is using more chlorine. The downside to just running it where it "should" be is having an algae outbreak.
 
Turniptruck said:
However, all calculations of chlorine generation inducate that I should be able to make more than enough during my current 12 hour run cycle.
Click to expand...
Correct. It's a choice, not a need.

But the overwhelming majority of folks who've tried 24/7 never went back.

You'll never wonder if you skimmed or filtered enough and FC will be topped off around the clock.

You're going to run half the day anyway. In the spring and fall the SWG needs less runtime but the skimming and filtering needs more. Adding 12 hours at 100something watts at low rpms may cost you $10 or $15 a month and you won't even know on the electric bill.
 
newdude said:
You'll never wonder if you skimmed or filtered enough and FC will be topped off around the clock.

You're going to run half the day anyway. In the spring and fall the SWG needs less runtime but the skimming and filtering needs more. Adding 12 hours at 100something watts at low rpms may cost you $10 or $15 a month and you won't even know on the electric bill.
Click to expand...
Completely understood. We usually put on the solar cover at night so the 24 hour skimming would be less effective, but SWG would obviulsy continue.

I'd consider the 24 hour run time. However, the SWG seem to be substantially underperforming. I would like to figure out why.
 
Very basic question and you may have done this, but have you physically inspected the cell for scaling? What do the plates look like?
 
Lake Placid said:
Very basic question and you may have done this, but have you physically inspected the cell for scaling? What do the plates look like?
Click to expand...
The 60K gallon cell I am using now has only a few weeks of run time on it. The plates are completely clean.

The current being drawn by the cell further indicates that it ~should~ be operating normally.
 
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