It was a quiet Thursday morning when the call came in. The client said they had shocked their pool the night before. A textbook move, done right after a long weekend of sunblock, sweaty cannonballs, and maybe a spilled drink or two. But now the water looked like cold broth. Suspicious. Very suspicious.
My job was simple. Find out what went wrong. Solve the mystery of the cloudy pool.
Chapter One: The Timeline
I arrived with a test kit, a pool brush, and a notebook. Always start with the timeline.
“When did you shock it?” I asked. “About 12 hours ago,” they said.
That ruled out impatience. It’s normal for water to stay cloudy for a few hours post-shock. But after 12 hours, it should at least be trying to look better.
“What kind of shock did you use?” They shrugged. “The one from the store.”
Vague answers. Not helpful. Could have been calcium hypochlorite, dichlor, or something worse. The plot thickened.
Chapter Two: The Equipment
The filter was a cartridge model. I popped the lid and took a look. It was caked in grime, sunscreen goo, and what looked like part of a pinecone.
“When did you last clean this?” “…Not sure.”
Case development. Filter neglect. A classic culprit.
The pump? Running, but barely. They had it on for six hours overnight. Not enough. Shock needs circulation, and six hours isn’t even close to what’s needed after a big chlorine hit.
Chapter Three: The Water Test
Test strips revealed more clues. Free chlorine was high. Good. But combined chlorine was also elevated. That meant the shock hadn’t done its full job yet.
The pH was a little high. That could reduce chlorine effectiveness. Another red flag.
So What Went Wrong
This wasn’t sabotage. This was user error. Too little pump time. A filthy filter. Possibly poor brushing after shocking. No clarifier yet, which was good. They hadn’t messed things up more.
My Prescription:
- Run the pump for a full 24 hours, no breaks
- Remove and clean the cartridge filter
- Brush the walls and floor thoroughly
- Retest chlorine and pH in the morning
- If water is still cloudy after 48 hours, add a clarifier and run the filter nonstop
By the end of day two, the pool had cleared. Another mystery solved. Another backyard safe for cannonballs. And another reminder that sometimes the enemy isn’t hidden. It’s just a dirty filter.
