How close did I come to killing myself?

HeatTransfer

New member
May 19, 2025
1
St. Louis, MO
I had just painted the pool, filled it, and was starting to add chemicals. I wasn’t enthusiastic about dropping 5 gallons of boric acid onto my nice new paint, so instead, I drilled some holes in the top of the bucket, shoved the hose in, and kicked it over into the pool like a depth charge. It worked great, I could see the cloud of boric acid coming out of the holes and absorbing into the water before being sucked into the main drain.

That worked so well, I thought I would do the same thing with the 8 lbs of cyanuric acid, that stuff takes forever to absorb, so I put it into the same bucket. The bucket was mostly empty so I thought I’d add the initial shock – about 8 lbs of calcium hypochlorite. I stuck the hose in, went and turned it on, filled the bucket with water, then I got distracted with something else. After about 5 minutes, I heard what sounded like a firecracker. The lid blew of my 5 gallon bucket “chemical diffuser” and then 3 or 4 minutes of “pop, pop, pop” like fireworks from the bucket.

What happened?

(CNOH)₃ + Ca(OCl)2 + H20 = ?
 
To anyone that reads this, do NOT mix pool chemicals.

Cal-Hypo is a strong oxidizer that releases hypochlorite ions (OCl⁻) and chlorine when dissolved or reacting. In dry form, it’s highly reactive with organic compounds. The oxidizing power of cal-hypo can cause cyanuric acid to break down or chlorinate rapidly, producing chlorine gas and nitrogen trichloride (The reaction isn’t stoichiometric).

C₃H₃N₃O₃ (s) + Ca(OCl)₂ (s) → Cl₂ (g) + NCl₃ (g) + CO₂ (g) + H₂O (l) + Ca-containing byproducts + heat

Chlorine gas is toxic. Nitrogen trichloride is explosive and toxic. The heat can cause the explosion, particularly when confined (like you did in the bucket).

You are very lucky.

 
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