Chlorine Guide
Liquid Chlorine vs Tablets: What Your Pool Actually Needs
Both sanitize your pool. But they behave very differently over a season, and picking the wrong default is one of the most common reasons pools slowly get harder to manage.
Trichlor Tablets
Slow-dissolving pucks used in a floater or feeder. Convenient and stable, they chlorinate for days without attention. But they are roughly half cyanuric acid by weight, so every tab permanently raises your CYA. They are also acidic, slowly pulling pH and alkalinity down.
Best for: Vacations, low-touch stretches, pools with low CYA that need stabilizer anyway.
Watch for: CYA creep. Test stabilizer monthly if tabs are your main source.
Liquid Chlorine
Sodium hypochlorite, poured directly. Works within minutes, adds zero CYA, and adds no calcium. The tradeoffs are hands-on dosing every day or two, a shorter shelf life, and hauling jugs. Slightly raises pH, which mostly balances out as chlorine is consumed.
Best for: Daily chlorination in most pools, especially anywhere CYA is at or above target.
Watch for: Freshness. Buy recent stock and store it cool and shaded.
The CYA math that decides it
A typical 3-inch trichlor tab weighs 8 oz and is about 54% CYA. In a 15,000 gallon pool, each tab adds roughly 3 to 4 ppm of stabilizer that never leaves. Use 3 tabs a week through a 20-week season and you have added over 200 ppm of CYA against a 30 to 50 ppm target.
In practice splash-out and backwashing remove some, but tab-fed pools routinely test at 100+ ppm of CYA by late season. At that level, chlorine is so suppressed that algae blooms in water that tests fine. The only fix is draining and refilling.
Liquid chlorine breaks that cycle completely. It adds sanitizer and nothing else.
The strategy most pools should use
Early season, low CYA: tabs are actually useful here. They chlorinate and build your stabilizer toward target at the same time.
CYA at target: switch your daily chlorination to liquid. Your stabilizer stays put and your chlorine stays effective.
Vacations and long weekends: a floater with a tab or two keeps the pool covered while you are away, and the small CYA addition is manageable.
What about cost?
Per pound of available chlorine, tabs usually look cheaper on the shelf. But the comparison flips once you price in the consequences: extra acid to counter high CYA, extra chlorine needed because it is suppressed, and eventually the water bill for a partial drain. Priced over a full season, liquid chlorine as the daily driver is usually the cheaper system.
Where to buy
The links below are Amazon affiliate links that help support Pool Clarity at no cost to you.
Know Exactly How Much Chlorine to Add
Pool Clarity calculates liquid chlorine doses for your pool volume and warns you when tab use is pushing your CYA too high. Free to use.
