SWG I have an Issue and a Theory What do you think?

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J

jfpetesn

0
May 9, 2010
27
Red Bud, IL
I have a 22,500 gal IG pool with a Pentair IC40 SWG. This is my 3rd season on the cell. I also have a Pentair Intelliflo VS pump. My first year no issues with chlorine production but last year and again this year I have noticed that I have to supplement with 6-8% bleach (about a gallon a week) to maintain my chlorine level at 3-4ppm. My FC slowly drifts down. I maintain my stabilizer at about 80ppm. I use the Trouble Free method. My water looks great but I wonder why the chlorine output is not enough to maintain my sanitizer levels. I have had to gradually increase the cell out put from 75% year one, 85% year two and this year I am at 100%. The cell is clean and maintained as directed. It has no scale. Salt level is 34-3500. I have my system cycle 4 3 hour runs for a total of 12 hours per day. I run my pump at 1150 rpms for a total flow across the cell of 30 gal/min.

It occurred to me today that perhaps if I increase the water flow across the cell to 1500 rpm/40 gal per min that I would potentially be exposing the cell to at least a 25% increase of NaCl molecules and consequently could expect an increase in chlorine production. Does this sound reasonable? Perhaps I have been running just enough water across the cell to have it function but not enough for max output. I know there is a law of diminishing returns in regards to water flow but I have been running my pump slow to save energy and get enough turns.

So I either have to increase my pump runs or increase flow right? I am also aware that the cell output drops with age and I probably am experiencing some of that. The only other thing I can think of is phosphate levels in the water. I have not tested for phosphates but am considering it. The pool is located in a rural area and is subject to lots of dust and some agricultural chemicals especially in the spring with planting. I don't use any pool chemicals that would introduce phosphates. It is filled with well water and so it is possible that it contains some natural phosphates. I do know it is naturally high in alkalinity at around 230 out of the tap. I have got the total alkalinity down to about 130 and my CSI runs about 0.10-0.14 at all times so I am able to maintain good balance. This is a vinyl liner pool.

Do any of you have any other ideas? I have had a pool for 30+ years and so I have had lots of experience but learn something new all the time,

Thanks
Jeff
 
Interested to hear re: plate wasting and molecules, but I did notice 3-4 PPM FC and CYA 80 which for me would be edgy on the low end. You've probably already done this, but just wondering about an OCLT to rule out a nascent algae bloom?
 
I have not done that but will tonight. The frustrating part is my water looks fantastic clear and sparkly. I just think that either the cell is not producing what it should or my demand is too much. I started with a FC of 4 yesterday afternoon. Added 1 gal of 6% bleach and would expect a result in the 6-7 ppm range. I speeded the up the pump too. This AM I got a 6 ppm reading so maybe I am on to something. It held last night and maybe a slight gain. I can see that the SWG is operating as there are bubbles at the returns.
 
I really thought the same thing. However, with the new variable speed pumps is it possible to have a low enough flow to satisfy the cell flow sensor but still not enough flow to allow full cell production? I think it is possible. I am going to do the OCLT tonight and watch my levels. I think I am seeing some increased production already but too soon to know for sure.
 
Flow of 30 GPM works in mine, but will be good to hear what you find out. If it were me, I'd raise it to 6 PPM FC with bleach based on PoolMath, then check after sunset to see where it's at for the start of the OCLT, then switch off the SWG until the morning test.
 
OK OCLT was negative. I had an overnight loss of 0.5 ppm. So I am going to watch this a few days and report back. Preliminary observation is that I am getting some increased production out of my cell. Yesterday was a hot humid sunny day and I was able to end the day with a 2 ppm loss at sunset. I did the OCLT last night so I can't say for sure but if I can hold my level through a hot day I feel I would have quite a bit of make up through the night so tomorrow will be interesting. If I still can't maintain a level then I guess I will check phosphates next.
 
You said you are running 4, 3 hour runs, could you try 2, 6 hour runs and see if that makes any difference maybe just before sunrise and the other one start at 3pm

I am using my phone so please excuse any spelling errors and short response. :)
 

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