Foam in a Rebuilt Water Feature

Persistent foam after relining often comes from contaminants—soap residue, paint, or sealant leaching. One rare case involved sewage seepage through a patch.

Fixes:

• Remove new materials (artificial plants, painted rocks) temporarily to test.
• Use pond-safe liquid fiber sealant (indoor only).
• Buy sealants from koi specialists.
• Defoamers are temporary; find the source.

No fish/plants? You have more chemical options.