Salt and FC level in non SWG pool

skoum

Well-known member
May 26, 2017
47
0
TX
#1
Hi guys,

I am considering switching to SWG and have question on the waterbalance.

For a SWG pool CYA level of 70/80 is advised, with FC levels between 3 and 6.
For a non SWG pool at the same CYA levels we recommend FC level between 8 and 11.

Whats the reason behind that ?

Shall I assume that if I dump enough salt in my non SWG pool to reach 3000 ppm I can make it run with a FC level between 3 and 6 (assuming 70/80 CYA)?
 

jblizzle

Mod Squad
LifeTime Supporter
TFP Expert
May 19, 2010
41,196
4
Tucson, AZ
#2
Not really. The lower FC is due to the fact that the SWG is more reliable at adding chlorine every day and due to some of the reactions taking place in the cell.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
8,968
0
Evans, Georgia
#3
some folks like the feel of salt in the water even when they don't use a SWG. That's cool, but it doesn't change their chlorine requirements at all.

The reason a SWG allows for lower FC is because the FC level remains so stable, no big highs and lows like you get when you are adding a large amount of chlorine at one time and expecting it to linger and last somewhat until the next dose. And the higher CYA for SWG pools is because of how stable yet low the FC is in those pools.

Maddie :flower:
 

skoum

Well-known member
May 26, 2017
47
0
TX
#4
Got it, thanks

Although I could argue that if I make my SGW run at a very high output so I cover my pool demand in say 2 hrs, then this is the same as a non SWG pool - the FC level won't remain stable.

Thoughts?
 

skoum

Well-known member
May 26, 2017
47
0
TX
#7
The higher CYA allows the lower amount of FC to linger longer.....

Maddie :flower:

Sorry but it still does not make sense to me ;)

Let say you have a non SWG pool at 80 CYA that loses 2ppm of FC a day (my case).

What is the difference between :

1- Using bleach in that pool every evening to increase the FC level from 4 to 6 (so it will never go lower than 4)

2- Having the exact same pool with an SWG that maintain the FC level between 4 and 6 ?

TFP method advises a FC level between 9 and 11 for the case #1, why should it be ?

FC is FC regardless the source (bleach or electrolyse), right ? Or is the FC created through SWG supercharged ? ;)
 
Last edited:

jblizzle

Mod Squad
LifeTime Supporter
TFP Expert
May 19, 2010
41,196
4
Tucson, AZ
#8
As I said before, there appear to be some things that take place within the cell that seem to help.
The non-SWG recommendations are made a little "human-proof" and are more conservative.

The absolute minimum the FC should ever be allowed to get is the SWG minimum listed. The non-SWG recommendations provide a little more wiggle room.
 
May 10, 2017
1,728
0
Hays, Kansas
#9
The swg adds FC for you, so it is more reliable than a human that might forget, or add too little. With the bleach chart skipping a day is not huge, swg chart a skipped day means 0 FC.

The reason for high cya with swg is to get your money's worth, and sometimes you have to use bleach to boost your FC, since the swg is more reliable than a human, a skipped day pouring bleach using the swg chart means you have to slam, a skipped day on the bleach chart is fine
 

skoum

Well-known member
May 26, 2017
47
0
TX
#12
A world record !! ;-)

No, it's just that I don't see any reason for a non SWG pool to maintain a FC twice higher than a SWG pool if you check your pool and add chlorine every day.

From what I understand above this is advised to make sure it does not go bad if you forget to add chlorine for a day or two.

There might be some stuff happening in the SWG cells that make the FC more efficient but I can't see any proof of that and I am doubtful about it. So I will give it a try.

An by nature I like to try new stuffs and be contrarian a little bit ;)
 
May 10, 2017
1,728
0
Hays, Kansas
#13
Dude, FC is FC, a swg it just a thing that dribbles it in your plumbing.

The bleach chart is a proven method on not having any problems, ever. If it doesn't work that $3 you saved will cost $30-$50
 

skoum

Well-known member
May 26, 2017
47
0
TX
#14
Exactly, FC is FC, so why advising 4-6 in one case and 9-11 in the other, at same CYA level.

That's not about spending less on bleach it's about trying to understand is there is any strong reason behind advising twice more FC in a non SWG pool.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
8,968
0
Evans, Georgia
#15
Say you run your pump 12 hours a day.

Someone gives you 12 Hershey's kisses. You eat 3-4 right away, and a few hours later some more.. and within 6 hours they're all gone!

That's like adding iiquid chlorine. You have it but they're gone before you wanted. You want more.

But with a SWG you eat one kiss an hour and you have more so that you can enjoy them each hour. They last the entire 12 hours. You didn't gorge on a bunch at once and have nothing later... you spaced them out evenly, albeit just one each time, so that they'd last long.

Maddie :flower:
 

jblizzle

Mod Squad
LifeTime Supporter
TFP Expert
May 19, 2010
41,196
4
Tucson, AZ
#16
Maddie that is only true if one is running their pump a long time and has their swg set low. If I run my swg at 100% and only run for 4 hours while the chlorine level is spread out slightly it is all effectively added within that 4 hours and then sits idle for 20.

I think the o p keeps comparing the target levels for the swg and non swg pools. Perhaps the focus should be more on the minimums. The key to everything is to always stay above the minimum FC levels.
 

shoot-straight

Well-known member
May 17, 2016
45
0
Kennedyville, MD
#17
love my swg. love it. when it dies, and it will, i will surely buy another.

i have a variable speed pump (love that too), i run pretty high for 3 hours in am to really skim, filter and run my polaris. then i have it set on the lowest possible setting the rest of the day (like 8 hours). swg is set at 50%. cya at 50 or so. it works for me, no need to change it.
 
#19
i have always wondered / been confused by this. If the minimum per CYA level is the minimum (.05 %) then why does it matter how, where or when the chlorine arrives. As long as it never goes below that number.

now if the TFP method suggests a higher number for manual chlorination as a buffer to human forgetfulness then recommend higher doses for that purpose, but add that caveat as to why it is higher.

if you want to "target" a higher number with manual chlorination because of UV burn off and the addition of all the chlorine in one batch, again also explain as such.

The candy analogy, for me, makes more sense when talking about target FC not minimum FC. a lower target for a SWG makes sense because it is being replenished on a cycle. "a slow drip" instead of "deluge" of a one time event per day.
 
May 10, 2017
1,728
0
Hays, Kansas
#20
The percentage method of FC/cya is a proven method here, tried and fiddled with here with thousands of people.

For bleach or once a day additions it so you have zero problems, zero. We don't do

"try this and see if it works"

We aim for zero problems

It's lower on the swg chart because the FC level essentially stays the same all day, does not dip to far low