I've got about an 8K gallon IG vinyl pool. I understand that with SWG you want to size at least double the rated size, so for me 20K SWG unit is minimum. But is there a point where it is not helpful to go larger? Say, 60K gallon rated SWG, is there anything bad about going that large for a tiny pool like mine? I have oversized filter, oversized pump (variable speed Hayward Tristar 950), and that seems to be nice to have. Maybe just not cost effective to go bigger than 20k rated SWG, or?. I usually run my pump at 600RPM, though recently with the spring tree droppings have run it harder to get better skimmer action. I've been confused as to what SWG system I should get. Seems like Hayward is controlling online sales pretty hardcore, so not any deals that I can find. If I want automation, to go with my VS pump I would need to go Hayward. I couldn't find any automation that seemed worth the trouble for me (would also love to be educated on what I am missing about automation, but I think might just be I have nothing interesting happening in my tiny pool, and would only benefit with a bigger pool with lots of features or something), so I may go with something more generic for SWG. Sorry, started with one question but I've been thinking about the pool a lot these days and bet I am still completely missing the boat on many, many issues. TFP has been extraordinarily helpful as a reading source. Many thanks for everyone who has contributed.
Is there a point where oversizing SWG is not beneficial?
- Thread starter OKDrDave
- Start date
Great question. To produce more or less chlorine, SWGs vary their runtime. Running at max setting will result in the SWG being turned on almost 60 minutes out of every hour, whereas at 50% it will be running about 30 minutes out of every hour. They are rated for a certain total runtime. I think it's 10,000 hours for the Pentair, which comes out to several years of normal use.
So, let's say that you have a 20k gallon pool and a SWG with the same rating. Not only will you have to keep it at max setting, but you will probably have to pump day and night to keep up with the FC loss. By doubling the SWG size to 40k gallons, you can pump during daylight hours only and often at less than max settings.
If you were to go up to a 60k SWG you'd need even less runtime, which theoretically would make it last even longer. However, SWGs experience wear and tear even when they're not energized. Therefore, my guess is that a 60k gallon SWG probably wouldn't last 50% longer than a 40k gallon one, and whatever extra longevity benefit you would get may not be worth the price difference. Also, technology tends to become better and cheaper over time, so when your 20k gallon SWG bites the dust after 5-7 years you may be able to replace it with something a lot more efficient.
So, let's say that you have a 20k gallon pool and a SWG with the same rating. Not only will you have to keep it at max setting, but you will probably have to pump day and night to keep up with the FC loss. By doubling the SWG size to 40k gallons, you can pump during daylight hours only and often at less than max settings.
If you were to go up to a 60k SWG you'd need even less runtime, which theoretically would make it last even longer. However, SWGs experience wear and tear even when they're not energized. Therefore, my guess is that a 60k gallon SWG probably wouldn't last 50% longer than a 40k gallon one, and whatever extra longevity benefit you would get may not be worth the price difference. Also, technology tends to become better and cheaper over time, so when your 20k gallon SWG bites the dust after 5-7 years you may be able to replace it with something a lot more efficient.
Last edited:
- Jul 21, 2013
- 65,062
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
No reason to go past 20K on a SWG when you have an 8K pool. I can give you a longer technical explanation but a 20K SWG will serve you fine.
Excellent! This helps me a lot. Thank you guys! Solid reasoning, I am thoroughly convinced.
I have this problem now. My PB put in a TCELL-15 rated for 40k gallons on my 11k gallon pool. At first, I thought it was a great problem to have.
The main issue is how easy it is to over-chlorinate the pool. My PB set my SWG at 50% for 24 hours a day to start and it took me 2-3 days before I got around to messing with it myself. You can imagine how high my FC was!
Then, I learned about duty cycles and proper scheduling for SWGs which helped immensely. Now, I have it properly set at 25% for 3 hours a day.
When I replace it, I may end up downsizing to the T-9.
The main issue is how easy it is to over-chlorinate the pool. My PB set my SWG at 50% for 24 hours a day to start and it took me 2-3 days before I got around to messing with it myself. You can imagine how high my FC was!
Then, I learned about duty cycles and proper scheduling for SWGs which helped immensely. Now, I have it properly set at 25% for 3 hours a day.
When I replace it, I may end up downsizing to the T-9.
- Jul 16, 2012
- 7,282
- Pool Size
- 27000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
True, though the Hayward does allow for tuning down to the single digit %'s below 10 so it's pretty flexible. Though that might only be with automation, or maybe that was another system that changes w/ and w/o automation.
Hopefully you have a separate timer for the SWCG and taking full advantage of the vs pump to skim the pool for longer periods using low rpm.
I had the same debate with myself when I got my SWG. I have a 23k gallon pool was was deciding between the RJ45+ and the RJ60+. In the end, I went with the RJ60+.
Because I generally leave the autocover closed when we aren't using the pool, my chlorine use is very low. Luckily, the RJ+ series supports 5% increments, because otherwise I'd constantly be modifying my pump runtime. I definitely could've gotten away with the RJ45+, but it isn't like the RJ60+ is a problem.
Because I generally leave the autocover closed when we aren't using the pool, my chlorine use is very low. Luckily, the RJ+ series supports 5% increments, because otherwise I'd constantly be modifying my pump runtime. I definitely could've gotten away with the RJ45+, but it isn't like the RJ60+ is a problem.