Chlorine levels staying low with SWG and high phospates

MeSue

LifeTime Supporter
Jul 29, 2007
351
Florida
Hello,

I have a peculiar problem I would like some thoughts about.

Several months ago--mid-September--I tested my water and the chlorine was non-existent. CCs were also low--0.5. The water was staying clear but there was algae growing in some of the waterline tile grout which has been pitted and cracked in some places since we moved here 4 years ago. In some places the pitting has created holes in the grout leading to recesses behind the tiles. And I was lax about scrubbing it this year because I knew we were getting it redone soon. This was around the time we were getting estimates

When I got the no chlorine result, I thought something had gone wrong with my SWG. So my husband cleaned the thing real good and I was looking at the user guide and it said high phosphates could be a reason for no chlorine. I took a sample to a pool store and he said my phosphates were more than 4000. I think that's the highest his test strip would read. (He was using strips that day because they were having trouble getting supplies for their testing system.)

I decided not to treat the phosphates since I knew we would be draining the pool in January. That first day, I put the SWG on super-chlorinate and within a few hours the FC increased to about 2ppm. So I thought the SWG was working fine. I scrubbed the waterline real good and starting that night, I shocked the pool with LC until it had no overnight chlorine loss. Then it took many weeks for the level to naturally drop down to maintenance level, but when it did, I tested and balanced everything else. All this was about the time we were not swimming much anymore.

Ever since then, though, my chlorine levels have been very low all the time. Much lower than what I would expect from where I have the SWG set. So I guess my question is… does this sound like something that the high phosphates would be causing? I don't know what else to think. There's no visible algae now, but there could be stuff I am not seeing behind the waterline tiles.

Besides the tile issue, there are also several places from when we moved here where the Diamondbrite coating was scraped away showing the concrete underneath. We think either something fell in the pool at one time, or it was used as a skate park! Could something be leeching in through these unsurfaced places? We are having the entire pool resurfaced including replacing the tile starting January 12.

I guess I should get my tap water tested before they refill it in case it's the source of the high phosphates. Any other thoughts?
 

Mdragger88

Bronze Supporter
TFP Guide
Jun 1, 2018
4,417
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
Are you using your own test kit?
What is your cya level? Along with the other parameters..
Fc
Cc
Ph
Ta
Ch
Cya
Phosphates are mostly irrelevant if you maintain proper fc for your cya FC/CYA Chart
level thus eliminating algea.
Phosphates don’t use up fc - algae does. If u have no algae it doesn’t matter how much “algae food” (phosphates) you have. No one’s home to eat it.

The original cause of your algae was due to going below minimum for your cya.
This could be because you didn’t adjust your swg settings as needed based on your fc demand at the time or perhaps your cya or salt was low & the swg couldn’t keep up. Things can happen fast in sunny, hot,rainy, florida.
At any rate I suspect you weren’t quite done with your SLAM Process - maybe there were hidden spots that weren’t checked like a light niche or ladder rungs.
The solution is to Slam again being very diligent- which you may not wish to do since you are planning on draining quite soon.
That’s understandable.

After you start fresh be sure to adhere to the target 🎯 levels of FC/CYA Chart on the chlorine side until you can turn on your swg.
You don’t want to have to slam your newly resurfaced pool.
If phosphates are real concern of yours you need to test that yourself w/ Taylor k-1106 so u can trust the results.
Here’s some more info on the subject 👇
 

Turbo1Ton

Gold Supporter
Dec 26, 2019
1,218
NE Oklahoma
Pool Size
14500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I would also suspect your SWCG may be nearing it's end of life. SWCG have a finite number of hours that they are rated to work. You say you moved into the house 4 years ago. Any idea how old the SWCG was when you moved in? 5-7 years is generally a good run, from what I've gathered here on the forum. Being in Florida, yours likely works nearly all year round, since your water temps most likely don't get to the low temp cutoff point.

--Jeff
 
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MeSue

LifeTime Supporter
Jul 29, 2007
351
Florida
We installed the SWG shortly after we moved here so it is less than 4 years old.
I would also suspect your SWCG may be nearing it's end of life. SWCG have a finite number of hours that they are rated to work. You say you moved into the house 4 years ago. Any idea how old the SWCG was when you moved in? 5-7 years is generally a good run, from what I've gathered here on the forum. Being in Florida, yours likely works nearly all year round, since your water temps most likely don't get to the low temp cutoff point.

--Jeff

I am using my own TF Test kit. I'll have to post numbers later. I don't think the CYA got too low. I always top it off when it gets to 50.
 

Mdragger88

Bronze Supporter
TFP Guide
Jun 1, 2018
4,417
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
Do you test your own salt w/ the k1766? If not definitely get one. Relying on the cell readout alone isn’t advised. I know sometimes the heavy florida rains can dilute the salt quickly leading to lower fc production. Also as the cell ages/dies it can say the salt is low but in reality it’s not.

When you get back running after your resurfacing & startup period you can do some more trouble shooting of your swg.
Aside from/after performing the Overnight Chlorine Loss Test to rule out algae you can then also do the “OCGT”
To determine the generation level of your swg & if it’s on its last leg.

Here’s the synopsis 👇
With a target level of fc FC/CYA Chart
After dark test your FC using the 25 mL sample for 0.2 ppm accuracy.
Turn on your pump and SWCG, set the SWCG to 100%
Run the pump and SWCG all night long
Before sunrise test your FC using the 25 mL sample for 0.2 ppm accuracy.

If your SWCG is working the FC should go UP overnight. We may be able to calculate if it working properly if you tell exactly how long it ran at 100% and the FC rise over that period of time.
 
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MeSue

LifeTime Supporter
Jul 29, 2007
351
Florida
Do you test your own salt w/ the k1766? If not definitely get one. Relying on the cell readout alone isn’t advised. I know sometimes the heavy florida rains can dilute the salt quickly leading to lower fc production. Also as the cell ages/dies it can say the salt is low but in reality it’s not.

When you get back running after your resurfacing & startup period you can do some more trouble shooting of your swg.
Aside from/after performing the Overnight Chlorine Loss Test to rule out algae you can then also do the “OCGT”
To determine the generation level of your swg & if it’s on its last leg.

Here’s the synopsis 👇
With a target level of fc FC/CYA Chart
After dark test your FC using the 25 mL sample for 0.2 ppm accuracy.
Turn on your pump and SWCG, set the SWCG to 100%
Run the pump and SWCG all night long
Before sunrise test your FC using the 25 mL sample for 0.2 ppm accuracy.

If your SWCG is working the FC should go UP overnight. We may be able to calculate if it working properly if you tell exactly how long it ran at 100% and the FC rise over that period of time.
Yes, I test salt with the k1766 kit. My SWG does not have a readout.

Thanks for the synopsis. Will report back after the resurfacing...
 
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Newdude

Mod Squad
Gold Supporter
TFP Guide
Jun 16, 2019
14,491
NY
We installed the SWG shortly after we moved here so it is less than 4 years old
What’s your average SWG schedule ? We can kinda guess the lifespan. Say, usually 12 hours a day for 250 days (long season) times 4 years is 12k hours on a unit rated for 10k. There is a lot more to it if things that shorten the lifespan on top of that, but if you haven’t already, you are probably at least be close to end of life.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
3,724
Spring Valley, NY
One more thing come to mind regarding longevity of the cellis how often does it get a MA treatment to clean scale. The more it gets it the faster the coating on the plates deplete. Just a thought. Also water temperature is a factor this time of the year. Not sure what you have but all stop producing when the water gets somewhere below 60°.
 

MeSue

LifeTime Supporter
Jul 29, 2007
351
Florida
What’s your average SWG schedule ? We can kinda guess the lifespan.
I generally run the SWG at 50-75% capacity except for the hottest 3 months of the summer and that is with the whole system running 9-10 hours a day. August/Sept might have to bump it to 100% occasionally or do "Superchlorinate" after a party or something. When we have real winter weather for a prolonged period, I might cut the run time down to 5 hours. It is a CircuPool SJ40 with 5 year warranty, bought in March 2018. It's supposed to be self cleaning. We have never done a MA treatment and have only cleaned the visible build up on the cell a couple times by using a cleaning tool per the manual. The manual says nothing about using MA to clean. Water temp here has not been below 60 since probably last January. It's solar heated and we are still having a lot of sunny days.

Since my last post the pump died... on Christmas Day, thanks Santa! 🎅 So it has not been running at all. New pump arrived and got installed yesterday, but we're just waiting until after resurfacing to have a fresh start with everything. Resurface is on schedule to start in about a week and then the pool company does the first 10 days of chemicals, brushing, and maintenance. SWG can't be used for 30 days after.
 

Newdude

Mod Squad
Gold Supporter
TFP Guide
Jun 16, 2019
14,491
NY
I generally run the SWG at 50-75% capacity except for the hottest 3 months of the summer and that is with the whole system running 9-10 hours a day. August/Sept might have to bump it to 100% occasionally or do "Superchlorinate" after a party or something
With runtime all over the map lifespan is a bit trickier to nail down, but with your long seasons, You definitely got most if not all of its lifespan so far. Here’s to hoping that the little guy has some more left in the tank. :)
 
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