There are four common ways to keep chlorine in a residential pool, and each one has a personality. Understanding what each adds besides chlorine is the difference between a pool that stays in balance for years and one that drifts into a stabilizer, calcium or pH problem nobody can quite explain. Here is the honest comparison.
Trichlor tablets
The slow-dissolving pucks that go in a floater or an inline chlorinator. They are convenient, stable in storage, and deliver chlorine steadily without daily attention, which is why they are the most common choice.
What they add: cyanuric acid, roughly half their weight. Over a season the stabilizer climbs, and after two or three seasons it is often high enough to make chlorine ineffective. They are also strongly acidic, so pH and alkalinity drift down, requiring regular additions of soda ash or baking soda. Stabilizer explained covers the consequences.
Best use: as a supplement, or as the main source in a pool that gets meaningful water replacement each year.
Liquid chlorine
Sodium hypochlorite in jugs or carboys. It is the purest way to add chlorine: it dissolves instantly, adds nothing but chlorine and a little salt, and does not affect stabilizer or calcium. It raises pH slightly, which balances well against a pool that trends acidic.
The downsides are practical. It has to be added often, sometimes daily in high summer, it loses strength in storage, especially in heat, and it is heavy to carry. Owners who test and dose regularly love it. Owners who want to forget about the pool for a week do not.
Best use: the main chlorine source for an attentive owner, and the best choice for shocking.
Calcium hypochlorite
Granular cal-hypo is strong, stores well and dissolves quickly. It adds calcium hardness with every dose, which is a benefit in a pool with soft fill water and a problem in one that already runs hard. It raises pH. It must be pre-dissolved before adding to avoid bleaching the finish.
Best use: shocking, and regular chlorination where calcium is low. Less ideal as the daily source in a pool on hard well water; filling from a well explains why.
Salt chlorine generator
A salt system keeps a mild salt level in the water and passes it through an electrolytic cell that makes chlorine continuously while the pump runs. It adds no stabilizer and no calcium. The water feels softer and the chlorine level is steady rather than sawtoothing between doses.
What it adds: pH rises steadily, so acid additions become routine. The cell needs periodic inspection and cleaning, and it is a wear item with a finite life. The salt is mildly corrosive to some metals and some stone, which matters for coping, equipment and anything near splash. Saltwater vs chlorine and living with a salt generator cover the full picture.
Best use: an owner who wants steady chlorine with minimal daily handling and is prepared for the upfront cost and cell replacement.
Side-by-side
- Hands-off: salt, then tabs, then cal-hypo, then liquid.
- Cleanest chemistry: liquid, then salt, then cal-hypo, then tabs.
- Pushes pH up: salt, liquid (slightly), cal-hypo. Pushes pH down: tabs.
- Adds stabilizer: tabs only (and dichlor shock).
- Adds calcium: cal-hypo only.
What changes over a season
The effect of a chlorine source is cumulative. A pool on tabs from April to October ends the season with far more stabilizer than it started with, and lower alkalinity. A salt pool ends the season having consumed a good amount of acid. A liquid-chlorine pool ends it about where it began, with slightly higher salt. None of that is visible week to week; it shows up in the spring test and in the pool that suddenly will not hold chlorine in July. Tracking stabilizer, calcium and alkalinity monthly, not just chlorine and pH weekly, is how the drift gets caught while it is still cheap to correct.
A sensible combination
Many well-run pools use liquid chlorine or a salt system as the base, a few tabs early in the season to bring stabilizer to range, and liquid or cal-hypo for shocking depending on calcium. The point is to know what each product does to the numbers, test regularly, and stop using any product that keeps pushing a number the wrong way. The five numbers that matter is the place to start.
We set up sanitation on every pool we build across the Triad, including Oak Ridge and Advance. If you are choosing between a salt system and conventional chlorine on a new build, request a free consultation.