How big should I go?
- Thread starter dswwpb
- Start date
- Jul 21, 2013
- 53,016
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Put that in your signature. It is very relevant to the advice you get.
Your pool will likely be at the low end of 2-4 ppm of FC used a day due to the enclosure roof protecting the chlorine from sun UV.
- Nov 30, 2019
- 855
- Pool Size
- 8500
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
I thought I had the Pool Math app pretty much figured out until I started trying to follow this thread.
In the above quote, what does the term 'cycle' refer to? Is it the pump run time entered, 8 hours in this case, or is it the salt cell generation cycle, the 180 minute cycle in the case of my Hayward T-15 cell which would be 72 minutes/cycle or 216 minutes total of cell operation/chlorine generation in the example (40% at 8 hours) above?
Does the app take the salt cell generation cycle time into account in calculating the chlorine that is generated in the entered pump run time?
Yes, just make sure the lbs/day chlorine generation is correctly entered as this is a key component to the apps calculations.
- Jul 21, 2013
- 53,016
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
PM assumes you will run the cell in one daily run for the pump run time specified.
The difference is minor unless you broke up an 8 hour pump run into 8 1 hour pump/SWG runs in a day.
You don't tell PM the cell type, just the daily FC generated so it can't take into account SWG Generation Cycle Times - Further Reading
Signature updated. So if I want to keep 5 ppm FC in the pool do I need to input 5 in the FC generated box on the pool math calculator?
- Jul 21, 2013
- 53,016
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
How much FC you need your SWG to generate to keep your pool at a FC of 5 depends on what is your daily FC loss.
You have to determine your daily FC loss from daily FC testing. PM gives you a starting point for your SWG % setting. If your FC is dropping below 5 then turn your % up by 5%. If your FC is rising above 5 then turn your % down by 5%. After a while you will dial in a % that maintains a steady desired FC.
After you have the SWG % dialed in you still need to monitor your FC and make adjustments as weather and the seasons change your pool FC usage.
- Oct 25, 2015
- 5,184
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
DS,
Just to give you a comparison data point I live about 25 mi north of you with a slightly larger, screen enclosed pool. I converted a year ago to SWG using a Circupool Rj 30+. It runs at 40% and run time ranges from 3-8 hrs per day. So at the top of the range I'm adding 1.9 ppm which is right in the middle of Allen's range. Every pool is different but I hope this helps you get a feel from a close comparison. In general, larger is better for SWG and if it were my I'd go with the same and plan to level out at 30%.
Hope this helps.
Chris
Just to give you a comparison data point I live about 25 mi north of you with a slightly larger, screen enclosed pool. I converted a year ago to SWG using a Circupool Rj 30+. It runs at 40% and run time ranges from 3-8 hrs per day. So at the top of the range I'm adding 1.9 ppm which is right in the middle of Allen's range. Every pool is different but I hope this helps you get a feel from a close comparison. In general, larger is better for SWG and if it were my I'd go with the same and plan to level out at 30%.
Hope this helps.
Chris
That's not about the size of the SWG but about how to insert the correct numbers so that PM can figure it out. The size of the cell regardless has to be 2X the pool volume at minimum if not bigger. The easier it has to work to produce the needed FC the longer it'll live.
- Nov 30, 2019
- 855
- Pool Size
- 8500
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
PM assumes you will run the cell in one daily run for the pump run time specified.
The difference is minor unless you broke up an 8 hour pump run into 8 1 hour pump/SWG runs in a day.
I may be overthinking on this but:
If I run my pump for 6.4 hours at 10% my cell generates chlorine for 54 minutes.
10% of 180 min cycle = 18 min, x 3 cycles.
If I run the pump for 9 hours the salt cell still only runs for 54 min of three 180 min cycles generating the same amount of chlorine. If I enter 6.2 hours run time in the Pool Math app it shows it shows FC rise of (.6). If I enter 9 hours run time the app shows FC rise of (.8), about a 20% difference.
I guess the .2 is minor (though 20% error doesn't sound minor). Looks like the app doesn't take cell cycle time into account.
You do tell PM the cell type, you pick from a dropdown.
- Jul 21, 2013
- 53,016
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
The dropdown is just a lookup for a chlorine output number.
Yes, you are overthinking this.
PM is just an estimate to give a starting %. The actual FC generated depends on many external factors including an individual cells cycle time.
Hi there neighbor,
Yes this helps alot, thank you. Do you keep the pool as warm as I do (90-91*)
My situation is lot like Chris. A screened pool larger than yours with an RJ30. July and August requires me to run 8 hours at 45% at CYA about 40 and with that setting the FC ranges from 4.0 to 7.0 depending on weather. The rest of the year requires much less. That's not high duty for a SWG, I think an RJ30 would be plenty for you. A RJ45 would require less time and/or output so the cell might last longer but running my numbers I think I figured a 7-10 year cell life based on expected cell life in hours. I suspect the drive electronics won't last that long.
- Oct 25, 2015
- 5,184
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Most of the year, yes. This time of year we use the gas heat to that level 2-3 times per week. During the summer our solar heater alone keeps it at that level. I'd be fine with 88 or so but wife requires a "9 handle".
Hope this helps.
Chris
- Oct 25, 2015
- 5,184
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Keep in mind run time and % power settings affect life a lot. The other thing that's very important is water balance. I watch it very closely and maintain CSI within spec too. Controlling CSI within TFP limits reduces the propensity for deposits to form and this is typically what requires acid cleaning which reduces cell life. There is a thin coating of catalytic materials on the anodes and small amounts are removed each time you acid clean. If you keep all your chemistry within limits you will also be within CSI range. But I look at the calculated CSI each time just to be double sure. I inspected my cell at 6 months and it looked brand new. Pretty soon I'll check it again. I do read about people that have to acid clean several times per year and I have to believe this has more to do with water balance than run time.
Chris
Chris
Well I have to say I was fairly sure I was going with the 45 but I think Chris and Doug's numbers with the RJ30 have convinced me to go with the 30. Their pools are in the same climate as mine, under a screen like mine, run at high water temps like mine, use the same pump run times as me, yet both are larger and doing fine with a 30. I think you guys have saved me a couple hundred dollars. I owe you guys a beer or two. But thank you to everyone who has contributed. All of you have taught me an unbelievable amount of knowledge about SWG's in a very short time frame. If anyone can still make a case for the 45 for me I'm all ears but now I'm fairly certain it's going to be the 30.
Darryl
Darryl
- Jul 21, 2013
- 53,016
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
- Oct 25, 2015
- 5,184
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
DS,
I'm a little anal too. I also had a hard time with the same issue. This is where its so fantastic to have TFP. They have a very clear unbiased recommendation of 2X your pool size or better. Plus the reputation here of Circupool is great. My decision came down to:
- RJ 30 exceeds TFP recommendation
- Others here are happy with the brand
- Save a couple hundred $ for something else on the pool
- In 4 or 5 years I may need a new cell but it will at least have some warranty so quit analyzing and get on with it!
Good luck with your swg!
Chris
PS The savings helped me fund convert to VS pump (albeit the cheapo motor only approach). Now I'm seeing electric bill benefit.