Contemplating going SWG... salt cell suggestions

djdonte

Well-known member
Mar 25, 2019
290
Houston, TX
Use Poolmath. Chemical Additions. Select SWG and your model on the dropdown list. Set how many hours you run your pump and then select % generation values. Start at 3 ppm FC per day.
Raise your FC to target level for your CYA. Your Poolmath logs show 80 ppm CYA. So raise the FC to 6-8 ppm using liquid chlorine.
Makes sense. Thanks I had no idea you could do that with pool math... sounds like I need to bump up the cell and maybe run time. I am going to add about to gallon of liquid chlorine and adjust my run times. Last summer my pool used 3-4ppm a day in this weather.
 

mguzzy

Well-known member
Jul 8, 2015
1,251
OV, CA
Well now that we have 90 plus degree weather here I am ending up for 1.5 FC at the end of the day... I bumped it up to 50 percent and got the same at the end of the next day. Any ideas? Should I be running 100 percent? What do the amps and bolts displayed on the control box mean?
You said the temp was hitting the 90's.. you will find a higher CL demand when its hotter.. Its possible that is what you are seeing. And as the sun is higher in the sky, it hits the pool with more UV. You'll get a feel for it as the summer progresses.
 
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djdonte

Well-known member
Mar 25, 2019
290
Houston, TX
Thanks all. Last year my pool used 3-4ppm FC on super hot days. Pool math says my cell will make 4 FC running 8 hours at 75 percent. for simplicity sake I dumped a gallon of 10 percent in, which should have me close to 10FC.
 

djdonte

Well-known member
Mar 25, 2019
290
Houston, TX
I put enough bleach to raise my FC to 10 2 days ago and have been running my cell 75 percent for 8 hours which should generate 4.0FC per day. Right now the FC at the end of today is 3.5. Either I am using a ton of chlorine or my salt cell isn’t working like pool math says it is. Any ideas?
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
1,214
Spring Valley, NY
I put enough bleach to raise my FC to 10 2 days ago and have been running my cell 75 percent for 8 hours which should generate 4.0FC per day. Right now the FC at the end of today is 3.5. Either I am using a ton of chlorine or my salt cell isn’t working like pool math says it is. Any ideas?
I think it's time for an OCLT to see what's going before we blame the SWCG
 

Hootz

Bronze Supporter
Feb 5, 2018
176
Rogers, AR
To establish a base of average fc daily loss consider turning off the swg and using liquid chlorine for a few days. Test the FC level 15 minutes after adding to make sure the addition brings the level to expectation. Check the fc level close to the same time every day. If you see your average loss at 3-4 ppm with liquid chlorine that would bring the cell production into question. One other suggestion is to look at the cell when the controller indicates generation is occurring......small gas bubbles should fog the water leaving the cell towards the pool. I agree with your calculation that 8 hours at 75% should add 4 ppm.
 
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djdonte

Well-known member
Mar 25, 2019
290
Houston, TX
Since I passed OLCT, I was also thinking of running it for a certain amount of time at night and then measuring to see if I got the calculated FC bump. I have a bit of bleach but really don’t want to go buy more... I mean it’s pretty much the reason for going SWG.
 
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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
26,711
Laughlin, NV
As you said, do a reverse OCLT - an OCGT - overnight chlorine gain test.

Test your FC after the sun goes down. Run your SWCG for X hours at X %. Test the FC the next morning before the sun rises. See if they match.

The RJ uses a 180 minute cycle I believe. So if you run it for 6 or 9 hours you will get the most accurate reading.
 
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mguzzy

Well-known member
Jul 8, 2015
1,251
OV, CA
Honestly I never got this analytical with trying to match the pools daily FC loss with my SWG production... At this stage it was more fly by wire. I had a rough idea of where I wanted to be, especially after I got my pump runtime in the right range. Then I adjusted the % to fit keep my FC in line. I found there were too many other variables to predict like bather load (how many kids ended up in the pool on any given day and for how long) and variations in sun exposure (my pool is in the shade a lot, but it can get into the 100s temperature wise)..
 

djdonte

Well-known member
Mar 25, 2019
290
Houston, TX
As you said, do a reverse OCLT - an OCGT - overnight chlorine gain test.

Test your FC after the sun goes down. Run your SWCG for X hours at X %. Test the FC the next morning before the sun rises. See if they match.

The RJ uses a 180 minute cycle I believe. So if you run it for 6 or 9 hours you will get the most accurate reading.
Thanks I will do that. Now that I think of it I don't see any "fog of bubbles." Maybe just a few small bubbles here or there. Would the amp/volt readout on the control panel aid me in diagnosing at all?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
26,711
Laughlin, NV
Remember the cycle time. Say the cycle is 180 minutes. If set at 50%, the SWCG generates for the first 90 minutes, then is off the next 90 minutes.
 

djdonte

Well-known member
Mar 25, 2019
290
Houston, TX
When I got home from work yesterday it was still at 4FC which is odd. Either the salt cell did something or I used no FC during the day. 3-4ppm usage was last summer with liquid chlorine and 40-50CYA. This is my first summer with salt.

In any case I tested after the sun went down and got 4FC .5CC. I set the pump to run 6 hours with SWG at 100 percent which should produce 4FC. I got the exact same readings in the morning. So I guess I will call DSP on Tuesday and see what they say.