Pool Chlorine Types Compared: Which One Should You Buy?
All four options below put the same thing in your water — hypochlorous acid, the stuff that kills algae and bacteria. The differences are strength, price per ppm, and what else they dump into your pool. Here's the honest comparison.
The four options at a glance
| Type | Strength | Adds to water | Best for |
|---|---|---|---|
| 6–12.5% Bleach (liquid) | 6–12.5% | Nothing but salt traces | Everyday dosing — the purist's choice |
| Cal-Hypo (granules) | 56–78% | Calcium — raises CH | Shocking; soft-water pools |
| Trichlor tablets | 90% | Cyanuric acid — raises CYA fast | Slow floaters in small doses only |
| Saltwater system (SWG) | Makes it on-site | Salt (~3,200 ppm, one-time) | Hands-off daily chlorination |
The trade-offs nobody explains clearly
- Trichlor is a CYA pump. Every pound of trichlor adds roughly 0.6 lb of cyanuric acid. Float a tablet all season and your CYA can hit 100+ ppm — which locks your chlorine into slow-release mode and can force a drain. If you use tabs, test CYA monthly.
- Cal-hypo is a calcium pump. Great for vinyl and fiberglass pools that run low CH; a scale machine for plaster pools already at 400 ppm CH.
- Bleach adds nothing. It's spent chlorine plus a pinch of salt. That's why experienced pool owners (and sites like TroubleFreePools) treat plain bleach as the baseline — you control everything else separately.
- Salt systems don't taste like the ocean. At 3,200 ppm that's 1/10th of seawater. The generator makes chlorine continuously, so daily maintenance is lowest — but you still shock, and the cell needs cleaning every 3–6 months.
Cost per ppm: the number that matters
Price per jug is marketing. Price per ppm per 10,000 gallons is reality:
- 6% bleach: ~$4/jug → roughly $0.40–0.50 per +1 ppm in 10k gal
- 12.5% pool bleach: similar or better per ppm, half the carrying
- Cal-hypo 68%: ~$5/bag → $0.60–0.80 per ppm, plus the calcium
- Trichlor: convenient, but usually the most expensive per ppm once you count the CYA problem
Wholesale truth: for daily dosing, plain bleach usually wins on price and purity. For shocking, cal-hypo works fastest. For maintaining between doses, trichlor in a floater is fine if you watch CYA.
Our recommendation by pool type
- Concrete/plaster pool: bleach daily + cal-hypo for shock
- Vinyl/fiberglass pool: anything works; cal-hypo conveniently manages low CH
- Busy households: saltwater system — the upfront cost buys back your Sundays
- Small above-ground pools: 6% bleach from the big-box store is unbeatable value
Dose any of them precisely
Whichever you buy, don't guess the amount: our chlorine calculator handles bleach, cal-hypo and trichlor with exact per-product strengths. Saltwater owners: the salt calculator gets your startup dose right, and the CYA calculator protects it all from sunlight.