Botanic Garden >> Gardening > >> Question and Answer >> Pond and Water Gardening

High pH, Green Water in Large Pond: Peat, Barley, Patience

17x24 ft pond, 3 yrs, new pump/waterfall, only 1 week clear. Green water, Microbe-Lift, no feeding. 2 biofalls, skimmer, 3200+6600 GPH pumps. 40% plant cover, anacharis. High pH, alkalinity, hardness. Asks pH adjustment, fish danger.

pH & Green Water

Ideal pH 7.3–7.5. High pH alone ≠ green water.
Green water = nutrients + light.
Fish not in danger from moderately high pH.

Stabilize, Don't Chase pH

Pond peat (nylon bag in filter) buffers pH gently.
Barley straw inhibits algae.
Plants: Increase cover to 60%.
Algaecide: Short-term, clumps algae for removal.

System Seems Solid

Good pumps, filtration, bacteria. Green happens. Peat + barley + plants + time = clarity.

Pond and Water Gardening: Keeping a Water Lily and Angelfish in a Vase; Mosquito Fish Die Overnight in New Pond: Troubleshooting; Koi Deaths After Hailstorm: What to Do; Fish Dying After Pond Relocation; Raising Pond pH Safely: From Acidic Well Water to Koi-Ready Conditions; Dead Koi After Spring Startup: Salt or Not?; Goldfish Dying Slowly: Mystery in 4,000-L Pond; Fish Deaths After Animal Carcasses in a Garden Pond; Mass Fish Loss in 700-Gallon Pond: Diagnosis & Recovery Plan; New Pond Suddenly Clear: Is It Balanced? Will Fish Ruin It?

Garden Articles

Baby Goldfish Die After Owner’s Overnight Absence: Water Chemistry Suspect

Winterizing a Small Goldfish Pond in Texas

Chlorine Overdose from Forgotten Hose: Saving Koi

Mass Fish Kill from Oxygen Depletion: Bubbles, Overstocking & Blue Dye Mistake

Keeping Trout Alive in Summer Heat: Oxygen, Temperature & Stocking Limits

Catfish Turning White: Water Quality, Diet & Runoff Investigation

Foaming Pond: Why It's a Sign of Poor Water Quality and How to Fix It

Plants

Hard Water in New Pond: Peat Moss Bag Lowers pH Naturally

Emergency Pond Leak: Move Fish to Pool, Match Temp & O₂

New Pond Owner Loses Koi: Common Mistakes and How to Avoid Them

Setting Up a Small Goldfish Pond: Water Prep, Filtration, and Algae Management

Mysterious Fish Deaths in a Well-Filtered Pond: Troubleshooting Guide

Indoor Water Plant Bowls: No Fish, Year-Round

Blue-Green Water and Foam in Spanish Pond