SWG vs. chlorine -- any reason NOT to do it?

[Mario P]

Our ~20k Gal, in-ground, fiberglass pool is awesome.
So awesome in fact that it gets a lot of use from our 19 grand-kids, on top of us (live-ins).
During summer, we could have pool open (Opening automatic pool cover) for 6-10 hours a day (in full sun), and average 4-5 days per week.

With all chemicals in check, I averaged adding 2-3 gallons of 8.25% bleach per day.
3 gallons, multiplied by 20 days is about 60 gallons of bleach!
At roughly 3 bucks per gallon, that's almost $180/month.

When my pool was built 3 years ago, PB installed the 'automatic' tablet dispenser (it fits about 8 3" tablets).
At full setting (5), the dispenser is nowhere near fast enough to keep up with the demand.
CYA is good, ~45-50.

I'm trying to figure if we can benefit from SWG.
I don't mind the initial cost hit.
Beyond the benefits of salt water, is there any reason (financial or otherwise) not to switch to salt?

 

[mas985]

With all chemicals in check, I averaged adding 2-3 gallons of 8.25% bleach per day.
3 gallons, multiplied by 20 days is about 60 gallons of bleach!

Are you sure about that? There is something wrong here. You shouldn't need that much chlorine. Even in the heat of of summer, I add less than 1 ppm per day which is about a quart per day? You are adding 12-16x that amount.

 

[mknauss]

I am all in on the SWCG -- but I agree with Mark - if you are using even 2 gallons of bleach a day in a 20K pool, you are adding 8 ppm of FC per day. That is high. I would suspect either your CYA is really low, or you have a persistent algae bloom.

How are you testing your pool water chemistry?

As you have a Pentair system with automation, I would suggest getting at least an IC40 or even better an IC60. It should seemlessly plug into your system. As always, check with the appropriate experts at a pool supply house to be sure. We suggest InyoPools.

Take care.

 

[Topher55]

2-3 gallons a day is quite a bit. But you say you have 19 grandkids. I do know when I have a couple of four year olds in the pool for a few hours I loose an extra 1-2 ppm for the day. They drink lemonade and eat watermelon all day and never have to go potty....[emoji848][emoji6]

 

[smallsmx3]

Sounds like you need to slam your pool. You should try a OCLT. I was amazed at how little my pool chemistry changes after I Slammed my pool. Even after hurricane Irma and not circulating for a couple days.

 

[Mario P]

Sounds like you need to slam your pool. You should try a OCLT. I was amazed at how little my pool chemistry changes after I Slammed my pool. Even after hurricane Irma and not circulating for a couple days.

Why SLAM?
All other numbers are in line.
And after adding 3-4 gal. I do go from 0 to 4-5 ppm (tested few hours after water has a chance to circulate).
It's just that chlorine doesn't last.

 

[smallsmx3]

Why SLAM?
All other numbers are in line.
And after adding 3-4 gal. I do go from 0 to 4-5 ppm (tested few hours after water has a chance to circulate).
It's just that chlorine doesn't last.

That's because something in the water is eating the chlorine. That's why you should perform a OCLT

 

[Mario P]

i am all in on the swcg -- but i agree with mark - if you are using even 2 gallons of bleach a day in a 20k pool, you are adding 8 ppm of fc per day. That is high. I would suspect either your cya is really low, or you have a persistent algae bloom.

How are you testing your pool water chemistry?

tf-100

 

[mknauss]

And after adding 3-4 gal. I do go from 0 to 4-5 ppm (tested few hours after water has a chance to circulate).

I also would suggest a Overnight Chlorine Loss Test. One, if your FC is 0 at any time, that is not good. Second, if you add that much chlorine to your size pool, you should get way more than that amount of FC.

Only other item would be that your pool is much larger than 20K, or the bleach you are using is not nearly 8.25%.

Take care.

 

[mas985]

Why SLAM?
All other numbers are in line.
And after adding 3-4 gal. I do go from 0 to 4-5 ppm (tested few hours after water has a chance to circulate).
It's just that chlorine doesn't last.

That means you have a 60k gallon pool!!! But also, you should not need to add 4-5 ppm per day.

 

[Mario P]

Got it.
Thanks all.
I will SLAM the pool when we open it next year for sure.

Back to second part of the OP, no one has any problems with converting to salt?
Even if I cut my use of chlorine in half or more, I should still be ahead if I just convert to salt, right?
That's figuring on initial cost of SWG, the salt and electricity to run it, correct?

 

[TXHeat]

Why SLAM?
All other numbers are in line.
And after adding 3-4 gal. I do go from 0 to 4-5 ppm (tested few hours after water has a chance to circulate).
It's just that chlorine doesn't last.

Pretty new to the TFP methods, but something's not adding up. My pool is about 15K gallons and currently I get 1 PPM of chlorine per 20 oz. of 8.25% bleach. And yours appears to be over 5-6x that amount, albeit with a 25% or so larger pool.

As far as the salt system, every contractor that gave us a bid told us it wasn't a good idea due to the amount of natural stone we used and it would stain and ultimately cause erosion. Other than that, probably a benefit.

 

[mknauss]

Data indicates that the overall cost is essentially the same. You either buy your chlorine up front with a SWCG, or you buy it every few days in liquid form.

Convenience is a huge plus. The minus is a pH that will rise more quickly potentially. That depends some on your fill water. You also must run your pump long enough to generate the chlorine. I assume you have a VS pump. If not, then your electrical cost will potentially increase.

I would suggest checking your water chemistry issues now, by doing a Overnight Chlorine Loss Test. If you wait until next year, depending on how you manage your pool over the winter, you can open to a bit more of a mess than necessary.

Take care.

 

[smallsmx3]

Got it.
Thanks all.
I will SLAM the pool when we open it next year for sure.

Back to second part of the OP, no one has any problems with converting to salt?
Even if I cut my use of chlorine in half or more, I should still be ahead if I just convert to salt, right?
That's figuring on initial cost of SWG, the salt and electricity to run it, correct?

I would say go for it. Saves the Hassel of having to add chlorine. Creates other daily duties. Just make sure you get a cell rated for a pool double or triple the size. The bigger the better

 

[Divin Dave]

There's no reason at all not to go with a SWG. You will love that thing. I would never have a pool that didn't have one.

 

[Mario P]

OK, based on what I see in the TFP calculator, my target salt will be 2300 ppm, correct?
If that's the case, I'll need 423Lbs of salt.
What kind of salt am I looking for and where do I get it from?

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Data indicates that the overall cost is essentially the same. You either buy your chlorine up front with a SWCG, or you buy it every few days in liquid form.

Convenience is a huge plus. The minus is a pH that will rise more quickly potentially. That depends some on your fill water. You also must run your pump long enough to generate the chlorine. I assume you have a VS pump. If not, then your electrical cost will potentially increase.

I would suggest checking your water chemistry issues now, by doing a Overnight Chlorine Loss Test. If you wait until next year, depending on how you manage your pool over the winter, you can open to a bit more of a mess than necessary.

Take care.

Thanks for all great advise.
I live in New Mexico. Like Laughlin, it's high desert with no trees, just dirt blowing everywhere.
Because of that, we got automated pool cover.
It's a fiberglass pool and each year I've opened it up, it only needed chlorine -- water was still clear.
Unless there is a reason to deal with SLAM'ing the pool now, I would rather wait until spring so that I'm not doing the SLAM process twice.
I assume that I will need to do that even with switching to SWG, right?

 

[Jimrahbe]

mp,

Where did you get the 2300 number??? Pentair cells operate between 2800 and 4500... You want to try to be in the middle of this range..

Thanks,

Jim R.

 

[YippeeSkippy]

You also want to make sure to buy a SWG that is rated 2x-3x your pool volume.

You might want to test your water one day before the kids all get there, and again right after, to see just how much chlorine those extra bodies (along with the lemonaide and watermelon) use up. Your pool is very heavily used, day in and day out in the summer, so your chlorine demand is high.

Are you testing for Combined Chloramines (CC) also?

Maddie

 

[mknauss]

OK, based on what I see in the TFP calculator, my target salt will be 2300 ppm, correct?
If that's the case, I'll need 423Lbs of salt.
What kind of salt am I looking for and where do I get it from?

- - - Updated - - -



Thanks for all great advise.
I live in New Mexico. Like Laughlin, it's high desert with no trees, just dirt blowing everywhere.
Because of that, we got automated pool cover.
It's a fiberglass pool and each year I've opened it up, it only needed chlorine -- water was still clear.
Unless there is a reason to deal with SLAM'ing the pool now, I would rather wait until spring so that I'm not doing the SLAM process twice.
I assume that I will need to do that even with switching to SWG, right?

I would think you would want to add some chlorine throughout the winter. Would not take much. I assume you do not winterize, such as drain and blow out the lines? If you do, then that changes things. I run our system about an hour each day during the winter. We never have freeze issues though the pump turns on at 35F for protection.

You should not have to SLAM in the spring if you have no issues in the fall. You would simply raise your FC to your target level based on CYA (which you would increase to 70 or so if using a SWCG) and start your SWCG.

Take care.

 

[tdp]

If your FC is repeatedly falling to zero, as others have said, you have something else going on—probably a low-grade but persistent algae problem, possibly coupled with high chlorine use due to pee in the pool (urine and ammonia eat up chlorine like nobody’s business). I would say you need to figure out what is eating all that chlorine before you get a SWG. SWGs are great, but they only put small amounts of chlorine in over a long time vs. the large chlorine spikes you get with liquid bleach. When I open my SWG pool in spring, I have to use liquid chlorine at first until I can get the pool clean & get the CYA up enough that the SWG can take over (SWG pools need higher CYA than non-SWG pools). You said you have a fiberglass pool, which is great, but if you have fancy stone on your coping/deck, salt will erode it over time. Also, my pool railing is powder-coated, because salt can erode uncoated fixtures. Just some things to think about.