55,000 gal pool conversion to SWG?

Stephs2125

Active member
Apr 18, 2017
43
SE Michigan
Hello,
I am in the process of buying a house with an IG pool (what details I know at this time are in my signature).
I grew up with above ground pools and have had one much of my life, but they were always salt water pools. I would like to convert this one at some point but from what I've read here in the forums, one should double the SWG output (35k pool would need 70k SWG output).
I've been searching and it doesn't seem anyone makes a SWG that I could double based on this pools capacity (55,000 gal.)
Do any of you know of one that I am overlooking? Do I have to give up on having a salt water pool? Can I use two SWG's? What say all of you :)

Thanks!
Steph
 

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mknauss

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Bronze Supporter
May 3, 2014
43,965
Laughlin, NV
In your climate, if you are willing to run the pump 24 hours per day (a VS pump may be a good investment), a 60K SWCG will work. Especially the RJ60+ from Circupool. It has a 3.1 lb/day chlorine rating.
 

laprjns

LifeTime Supporter
Aug 14, 2012
518
Ellington, CT
Be careful using the manufacture pool size (i.e gallons) rating to select your SWCG. You really need to look at the amount of chlorine gas the cell produces in 24 hour. For example, the Autopilots PPC5 is rated at 80K gallon and produces 2.62lbs of chlorine gas per 24 hours. The RJ60, which is rated at 60K gallons produces 3.1 lbs per 24 hours. So in your 55K gallon pool, the RJ-60 will actually produce more chlorine per day (6.8 ppm) than the Autopilot PPC5 (5.7 ppm) .
 

Stephs2125

Active member
Apr 18, 2017
43
SE Michigan
Be careful using the manufacture pool size (i.e gallons) rating to select your SWCG. You really need to look at the amount of chlorine gas the cell produces in 24 hour. For example, the Autopilots PPC5 is rated at 80K gallon and produces 2.62lbs of chlorine gas per 24 hours. The RJ60, which is rated at 60K gallons produces 3.1 lbs per 24 hours. So in your 55K gallon pool, the RJ-60 will actually produce more chlorine per day (6.8 ppm) than the Autopilot PPC5 (5.7 ppm) .
Thanks! I've started some initial research along those lines thanks to Marty's comment above.
I'm curious though...do you know why the actual chlorine production doesn't dictate the number of gallons rated? What basis are they using to say "treats 80K" or similar? It seems odd to me - is it just a "marketing" thing?
 

laprjns

LifeTime Supporter
Aug 14, 2012
518
Ellington, CT
I'm curious though...do you know why the actual chlorine production doesn't dictate the number of gallons rated? What basis are they using to say "treats 80K" or similar?
I have no idea. There certainly is no industry standard. Last summer ( I had a lot of time on my hands due to Covid) I put together a spreadsheet of the many various SWCG s to determine if there was any consistency between the various manufactures in how they determine cell ratings. As far as I can tell there is none.
 
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cowboycasey

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LifeTime Supporter
TFP Guide
Jul 3, 2013
8,645
Southern OK
with 2 RJ 60's and a VS pump you could run your pump 12 hours a day.. with 1 RJ60 you could do 24 hours pump run and adjust the RJ60 as needed... A VS pump at 1200 to 1300 rpm should be good for the RJ cell :)
 

Stephs2125

Active member
Apr 18, 2017
43
SE Michigan
with 2 RJ 60's and a VS pump you could run your pump 12 hours a day.. with 1 RJ60 you could do 24 hours pump run and adjust the RJ60 as needed... A VS pump at 1200 to 1300 rpm should be good for the RJ cell :)
Thanks! Can you help me understand or point me to where I can learn the math/reasoning for needing two SWG's (@12 hrs) vs. one (@24 hrs). I mean, I understand the obvious 12 is half of 24 but why isn't the one rated to produce 3.1 lbs/day insufficient and requires to run 24hrs/day? How are you able to determine this so I can better understand?
I think what I'm struggling to understand is this: If a single unit is capable of producing 3.1 lbs (6.8 ppm) in a 24 hour period why isn't that enough? Why would I need two? In my experience, 6.8 ppm daily is significantly more than I'll need on the daily and should be able to reduce the run time to produce less if that is not needed, right? Obviously, I'm missing something but don't know what it is.
 
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Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
10,784
NY
Hey Stephs !!!
I think what I'm struggling to understand is this: If a single unit is capable of producing 3.1 lbs (6.8 ppm) in a 24 hour period why isn't that enough
It IS enough. It is *more* than enough. But cells have a life span of about 10k hours of use. If you run 24/7 at 100% then you will reach that end of lifespan quicker.

So we always recommend to go 2X for longer life, and more runtime options for folks with high electric costs and no VS pump.

******However****. Being as far north as you are, you have a much shorter season AND a much lower UV demand from the sun than they do anywhere along the southern border. So you can easily go with a 1x or whatever the math works out to. :)
 

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amwillg

Gold Supporter
Apr 5, 2021
38
Louisville, KY
Salt water pools generally run a higher CYA than manually chlorinated pools. CYA 60-90. Based on the FC/CYA chart for SWG pools, that's a target FC of ~6.
FC/CYA Chart

Using the "Effects of Adding" section of Pool Math app (free), 55K gallons would require 2.8lb chlorine gas to produce 6ppm FC. Do you actually need that much per day? No. The CYA will help keep much of that from being burned off each day, so your actual daily need will be less in order to keep the pool at FC 6. Likely anywhere from 1-4ppm FC production/day depending on season.

I have not checked other SWG rating systems, but I calculated out Autopilot cell production and pool ratings. They rate pool size based on producing 4ppm FC over a continuous 24hrs.

1 Cell: you have a variable speed pump that can run at a lower setting 24/7 if needed and not break the bank on electricity
2 Cell: you have a single speed pump (that you don't plan to replace with a VSP) that is cheaper to run 1/2 the day. This shorter pump run with 2 cells would make sense if you will save enough on electricity to pay for the 2nd SWG. Though, it would honestly be better to spend that money on a variable speed pump and get one cell instead.

As far as options, the RJ60+ or the Autopilot PPC5 would both work. The RJ60+ is likely cheaper. Depending on the season, you'll likely need to run pump at least 12hrs/day with either
 

setsailsoon

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LifeTime Supporter
TFP Guide
Oct 25, 2015
4,226
Palm City/FL
Steph,

Congrats on the new pool, sounds fantastic! Looks like you've gotten good answers to the questions you had. I'd only add one thing. You can use the Pool Math app to play around with run time and % power settings to see how two vs one chlorinators will benefit you. Do this in the "effects of adding" section. Our 2x suggestion is one that works well for most installations. Yours is a little different. The advantages of a 2x initial design are that you have way more flexibility over the life of your pool. If it's sized exactly to 1x you could be running maxed out initially and then have to add supplemental chlorine after the cell performance starts to degrade. This is normal and happens to all of them. Another advantage is that incremental capacity is usually cheaper when buying a new unit. In your case you'd have to buy 2. If it were me I'd go with one large to start with and see how this works for you. In your location it may well be fine. If not, you can always add another later using the methodology that is described in Allan's reference above.

I hope this helps and good luck with your BIG pool!!

Chris
 
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Stephs2125

Active member
Apr 18, 2017
43
SE Michigan
Steph,

Congrats on the new pool, sounds fantastic! Looks like you've gotten good answers to the questions you had. I'd only add one thing. You can use the Pool Math app to play around with run time and % power settings to see how two vs one chlorinators will benefit you. Do this in the "effects of adding" section. Our 2x suggestion is one that works well for most installations. Yours is a little different. The advantages of a 2x initial design are that you have way more flexibility over the life of your pool. If it's sized exactly to 1x you could be running maxed out initially and then have to add supplemental chlorine after the cell performance starts to degrade. This is normal and happens to all of them. Another advantage is that incremental capacity is usually cheaper when buying a new unit. In your case you'd have to buy 2. If it were me I'd go with one large to start with and see how this works for you. In your location it may well be fine. If not, you can always add another later using the methodology that is described in Allan's reference above.

I hope this helps and good luck with your BIG pool!!

Chris
Thank you! I will play around with the app to help further my understanding. I appreciated the time everyone took to reply. Have a wonderful weekend :)
 
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