20K SWG Experiment

[cowboycasey]

Hey everyone, I have been busy this summer but I was able to conduct a easy experiment this summer...

I would like to thank Don @circupool from Welcome to Discount Salt Pool - Saltwater Chlorine Generators - Chlorinators I bought the SWG from him for this experiment.


SWG: Circupool SJ20, 0.87 pounds of chlorine a day
Pool: 24 foot, 13,000 Gallon, Vinyl, above ground
pool has shade till 0900, direct sun till 1500 (3pm) then back to shade
Pool use: 3 grand kids aged 5 to 9 and 2 adults 2 days a week
trees: Pecan trees and limbs directly over the pool

I installed the SJ20 on May 29th and turned it on June 1st
normal install >skimmer>pump>sand filter>SWG>pool

Starting Water levels
FC: 5
PH: 7.6
CH: 120
TA: 90
CYA: 80
Salt: 3800



The first 2 weeks we ran the SWG 12 hours a day (0.44 pounds a day), the FC dropped to 2 and was not able to keep up with minimum FC

At 2 weeks we ran the pump/SWG 24 hours a day, this is how the pool was ran before the conversion to a salt water pool so nothing new. The SJ 20 was still not able to keep the FC above 3 at all times, It did stay above 3 FC for over a month up until the temps were over 100 degrees.. Once this happened the SJ20 just could not keep up.. I had to add 1 pound of Cal-Hypo shock to keep up 2 times, this would kick the FC from 2 to 8...

I was gone the first 2 weeks of Aug and was not able to check the FC, when I returned the FC was at 0.. I was able to SLAM the pool and bring it back within 2 days so it was not bad and probably only at 0 during the day and would recover during the night...

The SJ20 and all the other 20/25K SWG models just can not keep the FC above 3 with any size pool above 5000 gallons, the SJ model creates more chlorine than most of the other models. What is also not talked about much is the pump must be ran 24 hours a day to get the rated amount of chlorine out of these SWG's. You may save 50 to 200 dollars initially buying a smaller SWG but that amount is spent running the pump the first year not to mention the cost of the replacement cell because running the cell 24/7 you will replace the cell sooner..

I will be replacing the SJ20 cell with the SJ40, the SJ40 does not have any issues keeping up with this size pool, I only run mine about 8 hours a day during July and Aug... I will use the SJ20 as a backup/emergency cell.

I hope this helps everyone make an informed decision in buying a SWG

 

[JoyfulNoise]

Thanks for the write up but something's not right....0.87lbs of chlorine gas per day should have added 8ppm FC if the unit was running 100% output 24/7. So if the pool was eating up 8ppm per day, you had algae eating it up.

What is your typical FC loss per day if you switched to manual chlorination?

 

[JamesW]

Deleted.

 

[cowboycasey]

Matt, I was thinking the same thing, 0 FC loss on the OCLT... did the test twice during July to see if something was going on... now when I was gone for those 2 weeks in Aug it was at 0 when I returned, so it did not pass

I just do not think these 20K systems are actually making that much chlorine gas, We have heard time and again from people actually using these and its almost always they are frustrated even though they are doing things right... I have the same setup except cart filter instead of sand and full sun dawn to dusk, my setup has no issues running from 0630 to 1500... Mine is an SJ45....

What I really believe is happening is the system is making between 5 and 8FC / 0.5 and 0.8 chlorine gas a day, that coupled with being used on the weekend takes the chlorine down a little at a time and it just does not have the ability to keep up.... (I am still not sure how you do the math to get how much FC will be added by 0.87 pounds a day)

I may see if I can get over there every night for a week to see exactly how much is being used a day, just really busy this summer... With that said, this is the main reason I and other have gone to SWG's because we can't be there all the time, if it added 8FC to the pool per day there should be no way to ever get down to 0FC, even if it was used every night, not just 1 or 2 times a weekend.. say it used 3 to 5FC a day, it would always stay between 3 and 5FC... I know my SJ45 has been a rockstar and I have never had any issues keeping up... matter of fact I shoot for 5 to 10FC at all times now with no issues.


What should be happening is these systems being names for what they can actually handle, now the bigger systems do a better job than the smaller systems do..

SJ20=SJ10
SJ40=SJ20
SJ45=SJ25
RJ60=RJ40

T9=T10
T15=T20

IC15=IC7
IC20=IC10
IC40=IC20
IC60=IC40

Intex SWG = I5

Here is the thing, I now exactly how to fix it, just change the SWG cell out to an SJ40 and be done with it, but there are people that do not have that choice and can't afford to do that...

 

[JoyfulNoise]

0.86 lbs/day x 16 oz/lb = 13.9 oz/day chlorine gas

Put 13.9oz into the Effects section of PoolMath and select "Chlorine gas". Make sure your pool volume is correct and you'll get the ppm's of FC added in a 24-hr period. Ignore the salt increase and pH decrease part of the results as that only pertains to external chlorine gas injection, not chlorine generated in-situ from salt.

Any idea what your phosphate levels are? (....that's right, I used the "ph" word...and not the good one ?)

But yes, could be a cell performance issue. Unfortunately, it's next to impossible to check cells for proper output as they are not designed that way. Even the bench testers at pool stores just look at presence of chlorine. I suppose one could construct a small scale water volume with a known amount of chlorine neutralizer in it and then measure chlorine as a function of time to see when chlorine is first detected. But that would be fraught with lots of variables.