Defecting from team Stenner to RJ60+

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Sampo said:
This guy right here is 20% shareholder in CicuPool. And deserves it.
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Poolstored battled me for a couple pages that his stenner worked great for him. He couldn't grasp the no jug lugging thing. Like. He grasped it fully, but it never hits to the extent it should.

So he had a bunch of WELL thought out points and eventually won me over that his stenner worked great for him, and he shouldn't switch.

So then he switched because I told him he shouldn't. :brickwall:

IIRC on day 3 he sent me a message saying that SWGs were boring because he had nothing to do. (Which is AWESOME). On day 5 he sent me a message that he'd fill the pool in if he ever lost the SWG. 5 days. From I don't need it, to fill the pool in without it.

Yeah. It's a good time.
 
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Sampo said:
Ha ha! It’s 3,800 ppm by drops just now. I slightly overshot my target. Though RJ panel claims only 3,200.
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Makes sense that you think you can taste it... I think at 3,200 or so, you'd find it quite different.
But it's not something you should aim to micromanage unless you enjoy frustration.
 
I was aiming for 3,200 ppm. A log of my additions is below. I tracked this carefully since this seemed to be a good opportunity to confirm the volume of my pool (based on the change in the concentration of salt).

DateMeasured [Cl-] with K-1766 (ppm)Addition (lb of NaCl)Predicted New [Cl-]Notes
3/24/24​
1200​
4/14/24​
80​
1480​
Expect 3.5 ppm/lb
4/21/24​
120​
1900​
4/21/24​
2000​
Salt rose by 100 ppm, nominally more than predicted. But within resolution of test.
4/29/24​
120​
2420​
5/5/24​
200​
3120​
5/5/24​
2800​
Salt rose by 300 ppm less than predicted. Pool could be bigger than I believe. Net gain -200 (1 drop).
5/5/24​
120​
3220​
5/6/24​
3800​
Salt rose by 600 ppm more than predicted. Pool could be smaller than I believe. Net gain +400.


I originally determined the volume of my pool through very careful measurements using a laser measure (with repeated checks to confirm all distances), summing the volume of five geometric shapes. My final result (34,500 gal) was close to the PB specs of ~36,000 gal. To be conservative, I’ve always used “34,000” as the volume in PoolMath (so that I wouldn’t overshoot with chems). Up until now, innumerable PoolMath predictions for chemical additions have been incredibly accurate.

Unfortunately, when it came to the salt additions, the predictions showed more variability than I expected. Here are some possibilities as to why:
  • Test/user variance with the K-1766. But some of these measurements were repeated on the same day, with identical results. Even with perfect technique, the K-1766 has a resolution of only 200 ppm.
  • Perhaps I didn’t wait long enough for complete mixing of the water after the salt dissolved — on 5/5/24 I waited just over an hour, (though I thought I recalled a rule of thumb from TFP that 10 mins is enough), and I got the same result of 2,800 ppm on repeat tests from both the end where I added the salt and the opposite side.
  • I didn’t independently weigh the “40lb” bags of salt from Home Depot -- so I can't confirm if the logged additions were precise.

I probably should have taken more measurements of the salt concentration between pouring in the bags. But I was a little spooked about the toxicity of the silver nitrate, so I thought to minimize the number of times that I tested.

For what it’s worth, myRJ60+ has been claiming an average salinity of 3,200-3,400. Could it be that my “final” measurements (x2) of salt on 5/6/24 are the ones that are incorrect? That would resolve both the discrepancy with the dilution and with the readings from the cell. Now that I'm writing this, I realize I'll have to retest this weekend!



P.S. All this aside, I did start to taste the salt at least at 2,000 ppm. So 3,200 vs 3,800 might not have made a huge difference there. But fortunately, per wife: "It's nice! It's like swimming in the ocean!" 🫣😳🤔🤗
 

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Sampo said:
Perhaps I didn’t wait long enough for complete mixing of the water after the salt dissolved — on 5/5/24 I waited just over an hour, (though I thought I recalled a rule of thumb from TFP that 10 mins is enough), and I got the same result of 2,800 ppm on repeat tests from both the end
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Salt, CYA and CH may take a full day to register after being dissolved.

That doesn't mean that they need a day each and every time, just that it might. That's enough right there to make me give them a full 24 hours, everytime.

All the salt tests methods have a wide variance. You add a human element as well. Sometimes it be like it is. 🤷‍♂️

And case and point to creep up to target for the chems that aren't easily reversed.

You did good only overshooting a little. You probably won't need the mid season top off and it will drift down slooooooowly with rain overflow in PA.
 
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Newdude said:
And case and point to creep up to target for the chems that aren't easily reversed.
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Yup. Lesson learned. I used to be extremely cautious, but had developed some hubris given how accurate PoolMath had been!

Next up is CYA, which is currently at 40. I'll definitely go slow.

But first, help me understand why a SWCG pool needs a CYA>60 whereas a bleach/Stenner pool is fine with CYA>40??
 
Sampo said:
But first, help me understand why a SWCG pool needs a CYA>60 whereas a bleach/Stenner pool is fine with CYA>40??
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The swg takes many hours to add FC. During the peak UV of the day, you'll lose more than it can produce.

FC gets spiked right then and there with LC and can afford to drift down all day.

We'd rec LC a 50 CYA for some extra protection too, if it didn't burn them if they needed to SLAM. It would add 8 more FC to have to maintain.
 
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Hmm. That kind of makes sense. But not fully.

If an equal amount of chlorine is produced, whether continually or spiked, the minimum/trough should be the same. If anything, chlorine might fall lower in the bolus case, since chlorine loss is somewhat proportional to its concentration.

With my Stenner, I was adding bleach between 4pm and 5pm (and then testing around 6pm). If anything, I'd imagine that the trough at 3pm was lower than with the SWCG.
 
Sampo said:
With my Stenner, I was adding bleach between 4pm and 5pm (and then testing around 6pm). If anything, I'd imagine that the trough at 3pm was lower than with the SWCG.
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Still, you added your whole dose in an hour, and not 6, 12 or even 24. I could run the SWG only at night and it would entirely swing like a LC pool during the day, just with slightly less loss from the higher CYA.

Raising the CYA also means slightly less FC loss, which means slightly less SWG runtime each day, and a longer cell life. Not alot, but they're spendy.
 
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Ok I think I’m starting to get it… Less fluctuation with higher CYA makes sense, of course. It still seems weird that the recommendation for bleach users isn’t equally high as well — but I guess that comes back to your point about SLAM levels — and maybe takes in the risk that those pools get into trouble more easily and need more SLAMs!
 
Sampo said:
and maybe takes in the risk that those pools get into trouble more easily and need more SLAMs!
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My SWG is never too tired to add chlorine today. Or too busy. Or forgetful.

Of course it has its own issues like potential power faillures, electronics hiccups or low salt alarms, but it's still more reliable than people.

Like I said, if it wasn't for the harder SLAM, we'd rec LC pools at 50 CYA.
 
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I just added 6 lbs and used a T shirt tied up on my brush pole. This is an old pic but same idea. Dump it on the chest of the shirt and carefully ball it up before tying/securing

20220624_082127.jpg
 
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