Clearing Green Water in a Patio Fountain: No Fish, No Problem

A new patio fountain turns pea-soup green within days. You've tried algaecide and water changes, but the algae returns. Without fish or plants to consider, you have powerful options that aren't safe for living ecosystems. Let's clear this up for good.

Why Fountains Go Green Fast

Small water volumes, full sun, and tap water nutrients (phosphates, nitrates) create a perfect storm for planktonic algae—millions of microscopic cells turning water green. Copper piping may leach trace copper, which can actually inhibit some algae, but it's not reliable control.

The Nuclear Option: Chlorine Bleach

Since no animals drink from or live in this fountain, chlorine is the most effective, cheapest, and easiest solution.

• Add 1/2 cup of unscented 6% household bleach per 50 gallons of water (approx. 1:1000 ratio) weekly.
• Run the pump for 30 minutes to circulate.
• Chlorine dissipates in 24–48 hours (faster in sun), leaving the water safe for birds, pets, and plants—though don't let pets drink immediately after dosing.
• This kills algae, bacteria, and mosquito larvae instantly.

Alternative: Nutrient Starvation

If you prefer zero chemicals:

1. Use RO/DI or Distilled Water: Zero nutrients = no algae food. Refill with this exclusively.
2. Add Floating Plants: Water hyacinth, water lettuce, or frogbit shade the water and outcompete algae for nutrients. They need no soil—just float them. Remove excess weekly.
3. Barley Straw Extract: A natural algaestat. Add per label instructions. Works slowly but helps prevent recurrence.

What NOT to Do

• Don't use pond algaecides designed for fish-safe use—they're weaker and more expensive.
• Don't add soil or fertilizer tablets. That feeds the algae.
• Don't rely on the copper pipe. It's not a consistent treatment.

Maintenance Routine

Once clear, scoop debris (leaves, flowers) daily. They decompose into algae fuel. Monthly, drain 25%, wipe surfaces, and refill with RO/distilled water + bleach dose. Your fountain will stay sparkling with minimal effort.