Eliminating Foam on Pond Water: Dissolved Organic Carbons Explained

What Causes the Foam?

White, persistent foam at waterfalls and edges is DOC (Dissolved Organic Carbon). Sources include:

• Oils from fish food (some brands worse than others)
• Fish body slime
• Spawn (fish, frog, toad eggs and milt)
• Decaying organic matter

Fix It

1. 30% Water Change: Dilutes DOC immediately. Use dechlorinator.
2. Add Pond Salt: 1 tbsp per 5 gallons (non-iodized). Helps fish osmoregulation.
3. Fresh Activated Carbon: Place in filter media bag in high flow. Replace every 2-4 weeks.

Prevention

Feed high-quality, low-oil food. Remove excess food promptly. Skim surface debris regularly. Maintain good biological filtration to break down organics before they become DOC.