Right sizing SWG

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J

jshaley

0
Jun 25, 2014
5
Rochester NY
Hello,

Brand new above ground pool. 27' Diameter, 54" sides, 12-18" dish in center. When using this formula (diameter(27) x diameter(27) x average depth(4.5) x 5.9) I come up with 19,354 gallons.

Dealer equipped pool with the Hayward Aqua-Trol T Cell 5. The manual says it is rated for 18,000 max and their salt reference tables stop there. The cell itself has a sticker that says it is rated for 20,000. They are very new to SWG's. We are going with it because we love the SWG our old Intex pool had.

Is this cell big enough?

Hayward Tech Support says I need the in-ground Pool version rated for 40,000. Not the above ground 25,000 product or the in-ground 25,000 product but the 40,000?!?

I am thinking a SWG that is slightly undersized might need to run longer which will shorten its lifespan; but the prorated costs might even out when compared to the more expensive larger units.

Would welcome your thoughts.

John
 
Welcome to TFP!

We suggest a cell rated 1.5 to 3 times the pool size for several reasons. The cell's life span will increase when a larger cell is used due to not having to run it as long. Also, you will need to run the pump much longer than you should need to so it can generate the required chlorine for the pool which will raise your electric bill. If you have high electrical rates that can add up real quick.

I would opt for a cell that is rated 40,000 gallons.
 
Question then - I have a 40k gal cell in a 18k gal pool. Does the larger cell require more water flow to operate? In other words would a lower capacity cell run on a lower flow rate (and lower pump rpm?) Or are they the same?
 
They usually all have the same flow switch. The cell size will not impact whether or not it runs at a given flow rate.

You should have no problem running at pretty low RPMs, but of course you will just have to see what works for your setup.
 
the hayward cells dont list how many grams chlorine gas produced per hour at 100 percent
so makes it very difficult to compare one cell or brand to another
if you can get that information then you can make an informed decision
according to poolmath for a 20,000 gallon pool and 4ppm FC per day you would need 230 grams chlorine gas per day
if your cell is 25 grams you will need 9 hours at 100 percent
my cell is 25 gram that's why i chose that number
 
From the research that I can find on SWG's, cells that are rated in the 20,000 gallon range put out .6-.7 lbs. of chlorine which is about 10.4 ounces. Using PoolMath that will yield 4 ppm of chlorine in 24 hours at 100% output of the cell for a 19,000 gallon pool.
 

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From what I could find, the Hayward t15 is .60lbs per day. The other two models are the 25 at .70lbs per day and the 40 at 1.40lbs per day. I found that on a site that sells saltwater systems. So not sure how reliable that is but maybe it's in the ballpark for figures.
 
tookiesmom07 said:
From what I could find, the Hayward t15 is .60lbs per day. The other two models are the 25 at .70lbs per day and the 40 at 1.40lbs per day. I found that on a site that sells saltwater systems. So not sure how reliable that is but maybe it's in the ballpark for figures.
Click to expand...
The T-15 is the 40k cell, so i am not sure what the first sentence means.
 
Sorry about that. My typing got ahead of my brain. The T-Cell 15 (40,000 gal) is 1.40lbs. The T-Cell 9 (25,000 gal) is .70lbs. And the T-Cell 3 (15,000 gal) is .60lbs. But like I said, that is just a saltwater system seller site giving the lbs numbers. So you can take that with a grain of salt ;) for comparison.
 
I just purchased and installed swg, and I too struggled with sizing. I considered buying a high efficiency pump as well, which would have effected my pump run-time. I ended up not going with the variable speed pump. I realized that swg sizing is dependent on pump run-time, as well as CL generation capacity. Most swg, like the Hayward, are rated to produce capacity over 24 hours. Unless you prepared to run pump for 24 hours per day, you will need to right size the swg to your pump runtime. I pump 8 hrs per day, so I needed a unit with 3 times the capacity, to ensure it would keep up with demand.

When my pool is optimally setup and balanced, I use about 40 oz 12.5% Cl per day. That translates to a little more than .25 lb. Since I only pump 8 hrs per day, I need at least a swg cell with .75 lb per day. I probably could have used the Hayward 25000 gal using (T-9) but I opted for the added capacity of the 40000 gal T-15 cell. Had I gone with the smaller T-9, I might have had to increase pump time in situation of heavy usage or high CL demand. I opted to oversize for the reasons cited above.
 
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