First, let’s bust a myth: it’s not dead fish hiding in the filter. The smell comes from chloramines, chemical compounds formed when chlorine reacts with ammonia. Ammonia? Yes—from sweat, sunscreen, urine, and even those tiny bits of skin you leave behind.
Think of it this way: your pool is a giant, self-cleaning punch bowl. Chlorine is the party host, but when guests bring too much organic “dirt,” the host gets overwhelmed and creates that stinky byproduct.
Why Does a Clean Pool Smell Worse?
Here’s the irony: a strong fishy smell often means too little active chlorine, not too much. When chlorine levels are low, it can’t fully break down waste. So it forms chloramines, which are less powerful and smell like a dock on a hot day.
You might think, “I added chemicals—why does it stink?” Well, if you smell that fishy note, your pool is basically begging for a shock treatment. A big dose of chlorine will burn off those chloramines and reset the balance.
