How do I keep algae from coming back after a shock treatment?

“A shock treatment kills the algae you can see. The rest of the job is making sure it never returns.”

Once the green water is gone, the pool is not automatically safe from another algae bloom. You have to keep the water balanced long enough for the filtration and sanitizer to finish the job.

The Follow-Up Plan:

1. Keep Brushing: Even after the pool looks better, brush the walls and steps for a few more days. Algae can survive in tiny pockets.
2. Watch pH Closely: If the pH drifts high, chlorine becomes much less effective and algae can come right back.
3. Run the Pump Long Enough: Circulation is part of the treatment. The water needs to keep moving so the chemicals are distributed evenly.
4. Clean the Filter: Dead algae clogs filters fast. If pressure rises, clean it before flow drops.
5. Retest the Water: Make sure chlorine, pH, and stabilizer are still in range after the shock treatment.

Austin Detail: A lot of people stop after the water looks blue again. In Austin, that’s how the next algae bloom sneaks in during the next hot spell.

If you’ve shocked the pool once and the algae still comes back, the problem is usually circulation or an underlying chemistry imbalance, not just “bad luck.”

Sent from my iPhone while revisiting a pool in Leander.