The Salt Cell vs. the Sun
Set the salt cell, pump time, and pool demand, then watch
whether chlorine production finishes the day ahead or behind.
The setting is not a chlorine level. It scales this cell’s rated production while the pump is running; the pool’s daily demand is a separate force.
The left side is chlorine produced. The right side is modeled daily FC demand. The larger total moves lower.
At these settings, the cell makes 1.7 ppm while the pool uses 2.5 ppm, leaving a 0.8 ppm shortfall.
This is a production comparison, not an FC target or dosing recommendation. It assumes rated output scales linearly with setting and runtime. It does not model cold-water or flow shutoffs, scale, cell age, salt level, changing CYA, covers, bather events, or the exact time of day the pump runs. Test the water and follow the cell manual.
A salt-cell percentage is not an FC target
A salt chlorine generator makes chlorine while water is flowing through the cell. The percentage setting controls how much of that available production time the cell uses. It does not measure the pool’s free chlorine and it does not guarantee a particular ppm.
Cell size, runtime, and pool volume work together
The cell rating says how many pounds of chlorine it can produce in 24 hours at full output. The output percentage and pump runtime reduce that daily amount. Pool volume then determines how many ppm that amount can add: the same cell produces a larger ppm increase in a smaller pool.
The pool is using chlorine at the same time
Sunlight and contaminants from swimmers, debris, and the environment consume free chlorine. CYA, temperature, weather, and pool use affect the actual loss, so this explorable asks for daily FC demand instead of claiming to predict it from a few settings. A recent measured day can provide a useful starting estimate.
What the daily chlorine balance means
The balance is estimated chlorine production minus modeled daily FC demand. A shortfall suggests the current combination may not keep up with that assumed day. A surplus means modeled production is higher than modeled demand; it does not prove the pool is at the right FC level.
How to use the explorable
Find the cell’s rated pounds per day in its manual, then set pool volume, output percentage, and daily pump runtime. Set daily FC demand to a measured or reasonable assumed loss. Press Play one day to see the two sides accumulate, or move any control to compare the end-of-day result immediately.
Size a salt cell for a pool
Use the salt cell sizing calculator to compare cell capacity with pool size. For an existing pool, regular water testing is still the way to confirm whether output and runtime are maintaining the intended free-chlorine range.
Sources and model scope: The production formula follows manufacturer guidance that a salt cell’s percentage setting cycles its output during pump operation and uses rated pounds of chlorine per 24 hours. See the Pentair iChlor manual and current IntelliChlor ratings. The CDC notes that sunlight and contaminants reduce chlorine levels and recommends routine testing.