What Size Salt Cell Do I need and How Much Chlorine Does it Make?

Sizing a Salt Water System known also as a Salt Water Generator (SWG) can seem easy enough since each salt system rates maximum pool size in gallons for you already. But herein lies the problem when sizing a salt water system. The cell size may be rated for your size pool but that may not be in fact the correct salt cell size. Huh? Here is the reason why.

Let’s say your pool is around 18,000 gallons. I will use the Pentair Intellichlor for our example here. For this pool size, the salt cell that would be rated for 20,000 gallons is the IC20 which is designed for pools up to 20,000 gallons. So, it would be only logical to purchase a Pentair Intellichlor Salt System with the IC20 cell. But this is the wrong choice in my opinion. You should actually purchase the IC40 Salt System which is rated for 40,000 gallons of water.

Here is why. The IC20 salt cell will produce .70 lbs. of chlorine in a 24-hour period. This means with the pool pump running at full speed (3450 RPM) it will produce .70 lbs. of chlorine which is equal to about 3/4 gallon of 12.5% liquid chlorine. But who runs their pool 24 hours at the full 3450 RPM these days? With the advent of Variable Speed Pumps running your pool at the full 3450 RPM is not realistic. And who runs their pumps 24/7 during the season? I hope you see where I am going with this. In theory, the IC20 can produce .70 lbs. of chlorine. In reality, it will produce far less.

Let’s say you run your pool at 2600 RPM for 12 hours a day. That means at 3450 RPM the IC20 would make .35 lbs of chlorine or about ¼ a gallon of 12.5% liquid chlorine. But at 2600 RPM which is a lower speed it probably will make about .20 lbs of chlorine each day. Maybe 1/6 of a gallon of 12.5% liquid chlorine. If your pool is a heavy use pool or prone to algae or running with a dirty filter this probably will not be enough chlorine on a daily and weekly basis for your pool.

But let us put the IC40 salt cell in place of the IC20 in this equation. The IC40 will produce 1.4 lbs. of chlorine in 24 hours running at 3450 RPM. That is twice the amount of the IC20 and more than 1 gallon of 12.5% liquid chlorine.

So, running your pool at 2600 RPM for 12 hours will make closer to .70 lbs of chlorine or somewhere between 1/2 and ¾ of a gallon of 12.5% liquid chlorine. This could mean the difference between your chlorine level zeroing out every day or maintaining a good level at 2600 RPM for 12 hours a day. So the IC40 will produce twice the amount of chlorine as the IC20 regardless of how you set your pump to run. This is a huge advantage for any pool owner, and it makes adjusting the run time and chlorine production of your pool that much easier.

Another factor is the lifespan of the salt cell itself. The Pentair Intellichor cells are not cheap to replace. The IC series salt cells are rated for 10,000 hours of use. This means that after 10,000 hours the salt cell is finished, and you will need to purchase a new one. So if you have an 18,000-gallon pool and run your IC20 Salt System at 100% during the season to keep your pool chlorinated, figure to get 3-4 years out of that cell.

If you, in turn, run an IC40 salt cell at 50% output in the same pool every season you actually will get 20,000 hours of life out of the cell. So you will get 6-7 years of use from the larger salt cell since you are running it at only 50% of the output. So it actually makes sense to pay the higher upfront cost for the larger IC40 sat cell than the less expensive IC20 cell even though it is the one rated for your pool size.

Both in chlorine production and the useful cell life, the larger salt cell just makes more sense. Bigger is better in most cases when it comes to pool equipment and investing in a larger salt cell is a wise decision. I suggest always going with the larger salt cell and larger system when you can.

Pentair
IC20 20,000 gallon pool .70 lbs. in 24 hours
IC40 40,000 gallon pool 1.4 lbs in 24 hours
IC60 60,000 gallon pool 2 lbs in 24 hours
iChlor 15 15,000 gallon pool
iChlor 30 30,000 gallon pool

Hayward
T-CELL-15- for pools up to 40,000 gallons
T-CELL-9 - for pools up to 25,000 gallons
T-CELL-3 - for pools up to 15,000 gallons

Jandy
TruClear 35,000 gallons

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