Wait 15 minutes after adding algaecide

No, you shouldn’t jump in right away.

Most algaecides need time to circulate and mix into the water. If you swim too soon, you’re basically swimming in a concentrated cloud of chemicals that can irritate your skin and eyes. Not dangerous in small doses, but unpleasant.

Fifteen minutes is the standard for most common polyquat algaecides. Some copper-based ones might recommend 30 minutes or longer — check the label. In practice, if you ran the pump for 15 minutes and the water looks clear, you’re fine.

The real rule: wait until the chemical has fully dispersed. If you can see streaks or swirling where you poured it, give it more time.

If you’re not sure, the bottle will tell you. But “immediately” is never the answer.