What’s Inside a Trichlor Tablet? (And Why It Matters)

Chlorine tablets look simple: drop a few pucks in a floater or chlorinator and forget about it. But trichlor has rules, and if you don’t know them, you can end up chasing algae, fighting high stabilizer, or even staining a pool surface. I’m a long-time pool pro, and I walk through what trichlor tablets actually are, why they became so popular, and why “90% available chlorine” doesn’t mean they’re the right answer for every situation.

We dig into the chemistry that catches most people off guard: trichlor is a stabilized chlorine, which means it adds cyanuric acid (CYA) every time you use it. I explain how quickly CYA can build up over a season, why cyanuric acid doesn’t evaporate out, and what that does to real-world chlorine effectiveness. We also talk through the practical target that many pros use, keeping free chlorine at roughly 7.5% of your CYA level, and why a pool with high stabilizer can demand a much higher free chlorine level just to stay safe and clear.

From there, I get into the on-the-ground realities of pool maintenance: why trichlor dosing is so hard to “set and forget,” how water temperature and pump run time change tablet output, and the safety mistakes I want you to avoid. You’ll hear why tablets should never go in the skimmer, how floaters can burn steps, and why granular trichlor should be used sparingly to prevent staining, especially on vinyl and fiberglass pools where low pH can be brutal. 

• what trichlor tablets are and why they dissolve slowly
• how trichlor became the most common sanitizer over time
• the Biolab fire impact on tablet supply and pricing
• cyanuric acid as the unavoidable trichlor byproduct
• simple math for how much CYA adds up fast
• why higher CYA demands higher minimum free chlorine
• practical ways to manage CYA with partial drains and dilution
• why tablet dosing changes with temperature and pump time
• why tablets never belong in the skimmer
• floater and surface damage risks plus how to prevent them
• granular trichlor use for tough algae with heavy caution

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