Secondary SWG

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mguzzy said:
I just read through this thread.. Interesting problem to figure out. To answer your question. YES an IC40 is more than adequate for a 13K pool... and YES you can install multiple SWG's in parallel. Some controllers support that, some don't so you would have to add a second controller....

That said what else could be chewing up your FC in hot conditions. .. that what's what it boils down to.. You can throw more FC in there via jugs of LC or 47 SWG's wired in parallel to compensate but, we still haven't solved the mystery of were the FC is going. You say it happens when it gets hot or when it gets sunny? those are two different conditions.

So to throw my 2 neurons worth of brainstorming into the mix, I am reminded of the pool owner that could not figure out where is chlorine loss was until he posted some pics of his custom water features and sculpturer friend of his did (or something like that). But it turns out they had large bowls that retained water in the water feature and were a perfect breeding ground for algae growth. Do you have some kind of water feature or something attached to the pool that would behave that way?
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Thanks for the response.. No no water features.. Just a rectangular relatively shallow pool (~4.5' deep average) with a spa. The pool stays pretty much pristine....
 
mguzzy said:
Ah.. that makes sense. You might want to update the wiki to reflect that.
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It is really a design specific decision. In this case I think the benefits of lower flow through serial cells outweighs any performance benefit of parallel cells. It may change for a larger pool that has larger pumps.

The Wiki page says...

In general multiple cells should be connected in parallel for best performance. Although with two SWG cells in a residential pool a parallel or serial water flow will likely work fine.

With parallel water flow each cell gets the same salt concentration in the water for maximum cell generation performance.

Adequate water flow is required to provide flow through each cell and close each cells flow switch.

With a serial flow of water through cells there is a concern of lessening of salt concentration in water on the downstream cells. Although the conversion from chloride to chlorine only removes a few ppm of the salt. So, the effect is negligible.

The bigger issue is that the gasses created keep the blades from being completely wetted and that would be the primary reason for diminished capacity.

Series should probably be limited to 2 or 3 in series.
 
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ajw22 said:
It is really a design specific decision. In this case I think the benefits of lower flow through serial cells outweighs any performance benefit of parallel cells. It may change for a larger pool that has larger pumps.

The Wiki page says...

In general multiple cells should be connected in parallel for best performance. Although with two SWG cells in a residential pool a parallel or serial water flow will likely work fine.

With parallel water flow each cell gets the same salt concentration in the water for maximum cell generation performance.

Adequate water flow is required to provide flow through each cell and close each cells flow switch.

With a serial flow of water through cells there is a concern of lessening of salt concentration in water on the downstream cells. Although the conversion from chloride to chlorine only removes a few ppm of the salt. So, the effect is negligible.

The bigger issue is that the gasses created keep the blades from being completely wetted and that would be the primary reason for diminished capacity.

Series should probably be limited to 2 or 3 in series.
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Right.. so you have to weigh better flow performance with serial configuration vs a better SWG performance with a parallel configuration. There is no correct answer and it depends on the rest of the system that its being installed in.
 
Note:

Although the conversion from chloride to chlorine only removes a few ppm of the salt. So, the effect is negligible.
 
And in the end the pump is going to have to run at a higher rpm to produce the necessary flowrate to close each flow switch if the 2 SWG's are plumbed in parallel. The effect is a higher cost per hour to run the pump.

As has been suggested multiple times in this thread - run in series is the most economical from a cost/hour of pump runtime.

While most all of us who have responded think the OP's IC40 is more than adequate and there are other issues at play, the OP doesn't seem to want to investigate that further.
 

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Jimrahbe said:
S,

You do realize that the idea that you have to turnover X water per day is just a myth... right???

You just need to run your pump long enough to generate the chlorine you need.. Period.

The IC40 makes the same amount of chlorine no matter what the pump speed is, as long a the flow switch is closed.

Thanks,

Jim R.
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Yep I do..

I'd be satisfied turning over something even less than once a day if I could keep enough FC in the pool. And yes it is pretty simple concept that chlorine generation is based on run time, but that does assume a minimum flow rate which is considerably higher than the pumps most efficient speed . So you are effectively running your pump much longer than needed for basic filtration so as to get the chlorine needed. So if you turn the problem around and have more SWG capacity (larger or multiple units) you don't need to run the pump as long to as you said "you just need to run your pump long enough to generate the chlorine you need"

I get that I can run 24/7 and it would probably generate enough FC, but I'm not trying to solve the problem by using the most energy possible. And yeah I get running two SWG units doubles the energy when they on.. But it is still more efficient to run two than doubling or tripling the pump run time.
 
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mguzzy said:
For the sake of discussion... I am wondering if the pool equipment is sitting in the hot/sunny sun as well. If so, could the electronics in the controller box be affected by high temps and make the SWG operation less effective?... hmmmmm:scratch:
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We have heard of a few situations where the SWG is cutting on and off and not really generating continuously the way it should when powered. I have been reluctant to mention that possibility. It takes some luck to see that type of intermittent malfunction.
 
proavia said:
And in the end the pump is going to have to run at a higher rpm to produce the necessary flowrate to close each flow switch if the 2 SWG's are plumbed in parallel. The effect is a higher cost per hour to run the pump.

As has been suggested multiple times in this thread - run in series is the most economical from a cost/hour of pump runtime.

While most all of us who have responded think the OP's IC40 is more than adequate and there are other issues at play, the OP doesn't seem to want to investigate that further.
Click to expand...

You are right the OP already spent months investigating the other issues at play and isn't interested in that anymore. The chlorine discussion has been repeated in hundreds of other threads... The specific question of this thread was the best way to run multiple SWGs. and series would definitely be desirable so that the pump doesn't have to be run at elevated inefficient speeds. The only reason I was asking about parallel was that I noticed that commercial setups that use multiple SWGs are usually paralleled. But it may also be that some of those I've seen have several SWGs and maybe serializing doesn't make sense.

While some seem certain that there are other factors in play, my CC is reasonably low. If there were "other factors" it would seem that it would show up as an elevated CC, but it isn't. Increasing CYA a little from the 40-50 range to 70 seemed to have helped a little. Which leaves the question of if the SWG is working properly, which it seems to when the environment has less extreme. But I don't have any measurements to back that up.

Thus I think the advice in one of the early threads to run a test to determine the SWG performance. Thus that is my next step before going to a larger or multiple SWGs.

Thanks
 
mguzzy said:
For the sake of discussion... I am wondering if the pool equipment is sitting in the hot/sunny sun as well. If so, could the electronics in the controller box be affected by high temps and make the SWG operation less effective?... hmmmmm:scratch:
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Good point.. The pool equipment is subjected to full day sun from morning till evening. And it does seem to be blazing hot when working on the equipment. Not hard to put some reflective material in front of it and shield it a little.. I'll give that a try just for grins..
 
ajw22 said:
We have heard of a few situations where the SWG is cutting on and off and not really generating continuously the way it should when powered. I have been reluctant to mention that possibility. It takes some luck to see that type of intermittent malfunction.
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Yeah, I suppose it could be. I've never witnessed that. But anything intermittent is hard. I've got a security camera near there.. Maybe I'll point it at the SWG and zoom in and monitor it. .
 
Two things i would try before buying anything:
1. Slow down the flow just enough for the flow switch to activate(i run mine 1200rpms@98watts) and run longer times.
2. Buy a standard solution for CYA and compare your testing, the CYA test is very subjective, you might have less than you think.
 
I understand the OP wants to run their pump at the most efficient speed and time. Looking at the math it doesn’t add up with two SWG. I am one of those people that run my VS pump 24/7 365 don’t close my pool. I run for 22 hours at 1500 rpm and 2 hours at 2200. Higher speed was when I would add bleach to pool still run that way with SWG. It costs about $16 a month to run my pump like that. So if I cut run time in half I would save $8 a month or $96 a year call it $100. Adding a second SWG will cost roughly $1100. So it will take 11 years to break even. Plus in that time figure replacing the cell twice (once every 5-6 years). You are then behind another $1200 you can’t break even. There is efficiency for the pump and also cost benefit to look at.
 
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