Phosphates

ethany

LifeTime Supporter
May 23, 2009
527
Trenton NJ
I’m having a problem with my swg making chlorine. The water is balanced, salt is good, water is clear but I’m told phosphates might be the problem. I test my water with a Taylor test kit. I did have my water tested at a pool store also and my Phosphates were high, over 2500.
 

domct203

Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015
3,959
CT
I’m having a problem with my swg making chlorine. The water is balanced, salt is good, water is clear but I’m told phosphates might be the problem. I test my water with a Taylor test kit. I did have my water tested at a pool store also and my Phosphates were high, over 2500.
Can the pool pass an Overnight Chlorine Loss Test?
 

ethany

LifeTime Supporter
May 23, 2009
527
Trenton NJ
Thanks for reply, I will have to do that test. I have a cya of 70 right now so that’s gonna be a lot of bleach if I need to slam.
 

ethany

LifeTime Supporter
May 23, 2009
527
Trenton NJ
Ok I did the over night test.....

Fc- 3.0 ( no loss of fc over night)
Cc- 0
Ph-7.5
TA-90
CH-250
CYA-80

Water is crystal clear. What’s next?
 

domct203

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TFP Guide
Jun 3, 2015
3,959
CT
Ok I did the over night test.....

Fc- 3.0 ( no loss of fc over night)
Cc- 0
Ph-7.5
TA-90
CH-250
CYA-80

Water is crystal clear. What’s next?
Your SWG was off for the entire OCLT?

Your FC is too low for your CYA. Your daily target should be 6-8ppm, and never let it go below 4ppm. If you don’t have algae now, you will soon if you keep the pool at FC 3ppm. You really should have bumped it up with bleach last night when you saw that the FC was below minimum.
 

Swampwoman

TFP Expert
LifeTime Supporter
Apr 27, 2012
3,835
Grand Rapids, MI
Ethany, , just so you know, my phosphates have been much higher than 2500 because I used to use a phosphonic (HEDP) Metal sequestrant due to my well water — over time, it built up to 10x that much because it breaks down into po4. AND even at that level, it did not stop my swg from producing the FC needed ;)

What is the rating of total lbs of chlorine gas your generator produces in a 24 hour period? Check your mfg specs. Then use the bottom field in pool math to see how much FC that means per hour in your size of pool. Then calculate the hours and percentage you run it.

I expect you’ll find you simply have not run it enough for increased summer demand ;) You May also wish to inspect the cell for calcium scale buildup if the math doesn’t point you to a run time issue.

And here’s a link to the [FC/CYA][/FC/CYA] wh8cj shows you where to keep your fc for a trouble free summer ;)
 

ethany

LifeTime Supporter
May 23, 2009
527
Trenton NJ
My swg was off the entire night. I been running pump n swg 24/7 for 2-3 weeks now since I opened pool. I realize 3 ppm is low at a cya of 80. Before I started the OCLT I had to add 62 oz. bleach to get fc up to 3 ppm. It was 1.5
After running all day that’s what I ended up with.

Since it passed the over night test, I assume I do not have an algae problem but a salt water chlorinator problem???

I cleaned the cell just before I turned on swg but after slamming. It did have some build up but clean now.
 

domct203

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Jun 3, 2015
3,959
CT
Did you set your FC target with bleach first? A SWG is not designed to raise the FC from zero.

Use bleach to get the pool to 6ppm, then run the SWG to maintain the FC.

You’re SWG is almost 2X the size of the pool, it should be able to maintain FC.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,358
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I've read about a "reverse overnight test" that can determine if your SWG is outputting as it should. Hopefully someone in the know about it can describe how that's done. I've never done it myself, so don't want to steer you wrong...
 

ethany

LifeTime Supporter
May 23, 2009
527
Trenton NJ
Yes I set the fc with bleach......I will try going to 6 ppm tonight with bleach and do it again.

Is zero cc a good sign I’m done slamming? I’m thinking yes

- - - Updated - - -

Oh ok I’ll push to 6 today n set swg at 100% to see if it maintains
 

ethany

LifeTime Supporter
May 23, 2009
527
Trenton NJ
Ok thanks.....I’m starting to wonder if there is something to this Phosphates thing. I’m perplexed as to what to do next. Being in the middle of a heat wave doesn’t help matters
 

ping

TFP Expert
LifeTime Supporter
Jun 24, 2011
3,138
Long Beach, CA
Phosphates have nothing to do with it unless you already have algae. Phosphates are food for the algae and the more phosphates there is lets the algae multiply. The OCLT will rule out algae.

I would raise the FC to 10 and run another OCLT tonight with the pump running and the SWG turned off. I personally don't like to run an OCLT starting off with only 3ppm of FC.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
11,085
Franklin, NC
Dirk mentioned a "reverse OCLT" above as a way to determine if your SWCG is working. So, to do it-

As you are planning bring your FC up to about 6 this afternoon with bleach.
After dark test your FC using the 25 mL sample for 0.2 ppm accuracy.
Turn on your pump and SWCG, set teh 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.
 

domct203

Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015
3,959
CT
I think I’ll call it the “OCGT”, or Overnight Chlorine Generation Test” LOL
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,358
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Dirk mentioned a "reverse OCLT" above as a way to determine if your SWCG is working. So, to do it-

As you are planning bring your FC up to about 6 this afternoon with bleach.
After dark test your FC using the 25 mL sample for 0.2 ppm accuracy.
Turn on your pump and SWCG, set teh 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.
I think I’ll call it the “OCGT”, or Overnight Chlorine Generation Test” LOL

Thanks for fillin' in the blanks, guys!
 

ethany

LifeTime Supporter
May 23, 2009
527
Trenton NJ
Ok I decided to shock again. I dumped 8 gallons of liquid chlorine to get me to 31 ppm at a cya of 80 (according to CYA/chlorine chart) I had 6 ppm to begin with.

Two hours later the pool got cloudy. My ph is very high now for some reason.....off the charts. My reagents are new.....not sure what to do now.....

One more thing we did get about an inch of rain today
 

ping

TFP Expert
LifeTime Supporter
Jun 24, 2011
3,138
Long Beach, CA
The pH reading will give a high false reading when the FC is above 10ppm. For future reference, before you add chlorine the pH should be lowered to 7.2 at the start of a SLAM. Continue the SLAM until the pool passes all three requirements to complete the SLAM.
 

ethany

LifeTime Supporter
May 23, 2009
527
Trenton NJ
Oh ok thanks Ping..... I won’t bother testing ph til after shock is done. I had a over night fc loss of 8 ppm so I will continue. Thanks again