In the process of converting to SGW and confusing chemistry

yubbie2

Bronze Supporter
Apr 1, 2017
89
Houston, TX
Howdy everyone

Starting the process of opening my pool back up as the weather heats up, and decided to convert to SWG. I purchased the Circupool RJ-60 after 6+ months of research, and installed it yesterday. I'll post a separate installation thread for anyone that's curious.

But in the meantime, I'm dealing with some confusing chemistry issues. Here's the timeline:

Saturday: Pool had a bunch of algae after frankly being neglected most of the winter, and only occasionally tossing a puck or 3 into the filter basket in the off season. Dumped 2 gallons of 12.5% (though likely degraded down to 8%-9% by now) bleach into the pool and gave it a good scrubbing.

Sunday: Installed plumbing portion of SGW, tested chemistry. Results:
FC 0; CC 0; pH 7.8; TA 80; CH 250; CYA 45; temp - mid 70's maybe? The FC = 0 made me think my Taylor DPD powder may have been bad, since I had just added lots of bleach. Around 4pm I added 400lb of Salt to the pool, stirred it around, and then let the kids swim to further dissolve it. Pool looked a little cloudy maybe. I believe my pool is around 27,000 gallons, so the target salt is a little over 800lbs for 3600ppm.

Monday: Pool looks crystal clear, and as far as I can tell I can't see any salt in there (visually). Tested again, FC = 0 (or maybe a hint of pink). DPD powder must be bad. Turn on Circupool RJ60 - initially it says Salinity is 3600ppm, then drops a bit to 3400ppm, and then eventually 0ppm.

Drive to Leslies (I know, I know) to pick up a fresh bottle of DPD powder, which of course they're out of. While I'm there I figured I'd let them test it to see how my salt was doing (I know, I know, I hate them and don't trust their tests, but...). This is what they reported back:
FC 0.07; CC 0.14; pH 7.7; TA 88; CH 251; CYA 47; Iron 0; Copper 0.1; Phosphates 2479; Salt 3900.

How is this possible? How could my salt be 3900 after only 400lbs added. And are my phosphates eating my bleach? I know it's only been 24 hours since adding the salt, but it's all just super confusing. I have the Taylor salt test kit arriving Wednesday, and I've turned off the SWG generator for now until I can figure out what's going on. Any ideas?
 
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jark87

Silver Supporter
Jun 5, 2011
366
Flower Mound, TX
Pool Size
25500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Given the age of your pool, your salt level was probably already fairly high. Doesn’t sound like you tested for salt prior to adding. I’ve only owned a salt pool, but from what I’ve learned on this site, liquid or granular chlorine adds salt to your water. While I do all my own tests, I do let Leslies test my water whenever I go to their store. I just use it as a comparison and trust my own tests if there’s a discrepancy.

Your water clearing up with virtually no chlorine is a bit of a mystery though.
 

cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
6,804
Southern OK
What was your salt level before you added salt.. All chlorine you have put in before has salt in it so you were probably already at 2000 ppm salt when you put that 400 pounds in :)

Bring your FC up to 6 and do a Overnight Chlorine Loss Test before you start up the SWG. if the OCLT fails then do a SLAM Process If you are good turn on your SWG and it should be fine.. You will probably have to do a SLAM with FC of 0 but if it is clear maybe it will only take a few days...
 

yubbie2

Bronze Supporter
Apr 1, 2017
89
Houston, TX
See, I never realized using liquid bleach was raising my salt, so you're right - it was probably already quite high. Dangit.

Good call on the OCLT, I'll do that tonight. But should I be worried about the phosphates?
 
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yubbie2

Bronze Supporter
Apr 1, 2017
89
Houston, TX
Ok so it appears I passed the OCLT. FC is still hovering around 0.7-1.0. Should I kick on the SWG at full power all day and boost to FC of 3-4?
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
7,752
NY
Should I kick on the SWG at full power all day and boost to FC of 3-4?
The average loss of FC per day is 2-4 ppm. Possibly more with blazing TX sun or a fun day of swimming. If you have 4 PPM to start you can lose it over the course of the day but your SWG might take a full 24 hours to put it back depending on when you lost it, and when the SWG runs to replace it.

You need to treat the ‘minimum’, not as an acceptable level but as a DEFCON 5 all hands on deck level. Maintain a FC level so that when you lose some naturally, you still are ‘in range’ based on the FC/CYA Chart.

Many of us target the high end of the range, possibly a skootch more so that we will always fall into ‘acceptable’. It’s a great safety net for beginners and it works so well that a lot of us kept doing it once we learned how to not necessarily need the extra help.
 

yubbie2

Bronze Supporter
Apr 1, 2017
89
Houston, TX
The average loss of FC per day is 2-4 ppm. Possibly more with blazing TX sun or a fun day of swimming. If you have 4 PPM to start you can lose it over the course of the day but your SWG might take a full 24 hours to put it back depending on when you lost it, and when the SWG runs to replace it.

You need to treat the ‘minimum’, not as an acceptable level but as a DEFCON 5 all hands on deck level. Maintain a FC level so that when you lose some naturally, you still are ‘in range’ based on the FC/CYA Chart.

Many of us target the high end of the range, possibly a skootch more so that we will always fall into ‘acceptable’. It’s a great safety net for beginners and it works so well that a lot of us kept doing it once we learned how to not necessarily need the extra help.
That makes a lot of sense, thanks. I’m very comfortable with the family swimming at FC 7, and you’re right - full TX sun for 12 hours has a massive impact on FC. What I’m trying to determine now is how long it’ll take my Circupool RJ60 to boost me up to 7. I may need to supplement with some bleach to help it along
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
7,752
NY
I may need to supplement with some bleach to help it along
Exactly. And well done. If you need a small boost, the SWG can handle it. If you need a *now* boost, Just add a jug (?) and it’s done. Did you download the poolmath app yet ? It’s free and awesome. You just plug in your #s and it tells you what to add and how much to get where you need to be. We can even tell you where to get ‘it’ on the cheap.
 
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yubbie2

Bronze Supporter
Apr 1, 2017
89
Houston, TX
Exactly. And well done. If you need a small boost, the SWG can handle it. If you need a *now* boost, Just add a jug (?) and it’s done. Did you download the poolmath app yet ? It’s free and awesome. You just plug in your #s and it tells you what to add and how much to get where you need to be. We can even tell you where to get ‘it’ on the cheap.
Heh, thanks. The great thing about this forum is I usually have a gut feeling about the answer, but the hive mind gives me the confidence to actually do it :)
Here in Houston I’ve found a chemical supply company that sells 12.5% for under $2/gallon, and is conveniently a few minutes from my office. I really lucked out. So converting to SWG was not a cost savings move - I was just really bad about adding bleach every day or every other day, and vacations really screwed us up. Purely a convenience play.
 
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cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
6,804
Southern OK
Almost Always use liquid to raise your FC level.. it will not hurt your RJ to have it run at 100% for 24 hours or so to get 7fc and you have already paid for the chlorine.. In summer it becomes harder to raise FC level with a SWG but now you should have no problem :)
 

mgtfp

Bronze Supporter
Mar 5, 2020
975
Melbourne, Australia
Pool Size
66000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Astral VX 7T
Ok so it appears I passed the OCLT. FC is still hovering around 0.7-1.0. Should I kick on the SWG at full power all day and boost to FC of 3-4?

What was the FC at the beginning of the OCLT, did you bring it to 6ppm as @cowboycasey suggested? It needs to be at least 3ppm as described here: Overnight Chlorine Loss Test. You say FC is now hovering around 0.7 - 1.0, which makes me think that the starting FC wasn't high enough to make an OCLT meaningful. And did you get fresh reagents in the meantime, it sounded like your DPD-powder had lost its magic?
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
21,771
Bedford, TX
Yub,

Your cell will add about .6 ppm of FC to your pool per hour when set to 100% output. The "average" loss of FC is 3 ppm per day, but that depends on the location, the sun and your CYA level.

To generate 3 ppm of FC you should only need to run your cell for 5 hours, if set to 100% output, or 10 hours, if set to 50% output.

You can't really do a good OCLT when your FC is less than 5 ppm.. I'd dump in some liquid chlorine and get the FC up to 5 ppm just before starting the OCLT..

With a CYA of 45 in your area, the sun will eat the chlorine almost as fast as it is being made... I'd get my CYA up to 60 or 70. When I see my FC demand increase, it is almost always because I let my CYA drop below 60.. Note.. you want to pass the OCLT before adding any CYA..

Thanks,

Jim R.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,288
Spring Valley, NY
Yuppie,
As Newdude said get the FC target up to level now with a jug of chlorine and use the RJ60 to maintain whatever level you're aiming for. Your CYA is out of range for a SWCG pool and for now should be in the 60-70 range. Test the salinity with the Taylor K-1766 for the most accurate testing and don't trust Leslie's with it. Although it may actually be in the 4000 range the circupool RJ60 loves it there too. The main number in poolmath app you should be looking at is the CSI as that will take all your levels and let you know how insinc they are as a whole. Anywhere between 0 and -.6 should be where you want it all the time. You will extend the life of the cell buy it not getting scaled up and needing a MA cleaning which removes the coating from the cell plates. There are guys here including me that never need to clean the cell for a number of years already due to that CSI tracker.
 

yubbie2

Bronze Supporter
Apr 1, 2017
89
Houston, TX
Ok, this is great information. Thanks everyone - I didn't read the details about OCLT because I had done them in the past, but that was usually after a SLAM so my FC was always super high at the time anyway.

Order of operations:
  1. SWG to 100% today
  2. Early afternoon, add a bunch of liquid chlorine to get FC > 6
  3. Turn off SWG at sunset
  4. Start OCLR tonight (test with old and new DPD kit, though I think my old stuff is actually still good as stupid leslie's confirmed my test measurements)
  5. Finish OCLR before sunrise tomorrow
  6. If pass OCLR (FC would now be ~6-7), reduce SWG and start figuring out burn rate vs generation rate for long term SWG sustainment
  7. Start adding CYA to boost from mid-40s to mid 60's
  8. Likely dial down SWG once CYA is higher (as burn off rate will drop)
  9. Wait for Amazon to deliver my K-1766 kit on Wednesday and start adding that to my test regimen.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
21,771
Bedford, TX
Yub,

If you have done a SLAM before, then you are not doing it right.. :mrgreen:

You should only have to do a SLAM once...

Not sure what it is, but something is not right.

Thanks,

Jim R.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
7,752
NY
^^^^^. All of the above except #7. we always round up to the next 10. 41-49 is a 50 for example.
 

yubbie2

Bronze Supporter
Apr 1, 2017
89
Houston, TX
Yub,

If you have done a SLAM before, then you are not doing it right.. :mrgreen:

You should only have to do a SLAM once...

Not sure what it is, but something is not right.

Thanks,

Jim R.
Fair. I've had to do them after vacations, draining the pool for biblical storms, etc.