In the summer of 2021, pool service operators across North America confronted something few had prepared for: trichlor tablets simply weren't available. A fire at the BioLab manufacturing facility in Westlake, Louisiana in August 2020 destroyed one of the largest trichlor production plants in the country, and the combination of COVID-driven pool installation demand and supply chain disruption turned a production disruption into a multi-season crisis. Tablet prices tripled. Some markets saw 50-pound buckets jump from $75 to $250 or more — when they could be found at all.
The techs who navigated the shortage best adapted their chemistry programs quickly and, in many cases, permanently improved their approach. Here's what the experience revealed.
Trichlor (trichloroisocyanuric acid) had become the default sanitizer for residential pool maintenance — roughly 87–90% available chlorine by weight, slow-dissolving, convenient in tablet form. But trichlor comes with a chemical cost that the shortage made suddenly visible: every tablet adds CYA (cyanuric acid, stabilizer) to the water. At standard tablet use rates, a residential pool can accumulate 80–100+ ppm of CYA over a season without active management.
This CYA accumulation matters because high CYA slows chlorine's effectiveness significantly — requiring much higher FC levels to achieve the same sanitizing power. Many techs discovered in 2021 that their pools were essentially fighting their own chemistry system.
The most practical immediate alternative was liquid chlorine — sodium hypochlorite at 10–12.5% available chlorine. Already the dominant product at commercial pools and used by many residential operators for shocking, liquid chlorine became the primary sanitizer for thousands of routes during the shortage.
The chemistry advantages of liquid chlorine over trichlor are significant:
The practical disadvantages: lower concentration than tablets means more volume to transport and handle. Liquid degrades faster (6–8 weeks versus tablets' year-plus shelf life). And without any stabilizer, pools in direct sunlight can deplete chlorine faster between service visits.
Cal-hypo — available at 65–73% available chlorine — was the second major alternative. It's been used for decades, particularly by commercial operators. During the shortage, many residential operators who had never used it transitioned their routes to granular cal-hypo.
Key considerations:
Cal-hypo and trichlor are incompatible. Never store them in the same container or add them to the same pool at the same time without allowing full dissolution and circulation between applications. The reaction is exothermic and can ignite spilled material.
The shortage accelerated salt system installations dramatically. Operators pitched conversions to customers who were frustrated with chemical availability and cost spikes. A saltwater pool generates its own chlorine from dissolved salt via electrolysis — eliminating tablet dependency entirely.
Installation runs $1,500–$3,500 including the salt cell and control board. Ongoing cost is replacement salt (~50 cents/pound) and eventual cell replacement ($200–600 every 3–5 years). The value proposition during the shortage was compelling: never dependent on supply chain again.
The shortage revealed how many residential pools were operating with CYA levels so high that chlorine effectiveness was severely compromised. Techs who moved to liquid chlorine found that some pools — previously "maintained" at borderline chemistry — suddenly performed better because they stopped adding stabilizer with every tablet.
| CYA Level | Minimum FC Required | FC for Algae Prevention |
|---|---|---|
| 0 ppm | 0.5 ppm | 1 ppm |
| 30 ppm | 1.5 ppm | 2 ppm |
| 50 ppm | 2.5 ppm | 4 ppm |
| 80 ppm | 4 ppm | 6 ppm |
| 100 ppm | 5 ppm | 7.5 ppm |
The FC/CYA relationship is the most important table in pool chemistry. Managing CYA is how you ensure that the chlorine you're adding is actually working. Use SplashLens to calculate your FC targets based on your current CYA level — because the right FC number depends entirely on what's already in the water.
Many operators who transitioned to liquid chlorine during the shortage never went back to tabs as their primary sanitizer — or significantly reduced tab use in favor of liquid-primary with tabs for between-visit maintenance. The results: more predictable chemistry, lower CYA accumulation, and reduced pH instability.
The shortage was painful. The lasting effect was a more chemically literate industry with a healthier skepticism of single-product dependency.
SplashLens calculates dosing for liquid chlorine, cal-hypo, trichlor, and every other sanitizer — free, offline, every stop.
Open SplashLens Free →The 2021 shortage was triggered by a fire at the BioLab facility in Westlake, Louisiana in August 2020, which destroyed one of the largest trichlor tablet manufacturing plants in North America. Combined with COVID-driven pool installation demand and supply chain disruptions, the shortage created 3–4x price spikes and widespread unavailability throughout 2021.
The primary alternatives are liquid chlorine (sodium hypochlorite, 10–12.5%), calcium hypochlorite (cal-hypo, 65–73%), and saltwater chlorine generation. Liquid chlorine adds no CYA or calcium. Cal-hypo adds calcium but no CYA. Salt systems eliminate supply dependency entirely.
Yes — household bleach (6–8.25% sodium hypochlorite) and pool-grade liquid chlorine (10–12.5%) are chemically identical except for concentration. Pool liquid chlorine is more cost-effective per unit of available chlorine. Both are the cleanest form of chlorine — no CYA, no calcium added.
Cal-hypo adds no CYA — making it better for pools that are already CYA-heavy. It does add calcium. Unlike trichlor, cal-hypo should not be mixed with trichlor or added directly to a skimmer with tablets present — the combination is reactive.
Many techs permanently shifted to liquid chlorine for routine maintenance and moved trichlor to a secondary role. Salt system installs accelerated dramatically. Operators also learned to manage CYA more actively — the shortage revealed how many pools were operating with dangerously high stabilizer levels.