Building a Small Backyard Pond: Liner Sizing and Natural Look

Liner Calculation

Pond: 8 ft L × 3.5 ft W × 3.5 ft max depth. Liner needed: (Length + 2×Depth + 2 ft overlap) × (Width + 2×Depth + 2 ft overlap) = (8+7+2) × (3.5+7+2) = 17 ft × 12.5 ft = 212.5 sq ft. Your 6 ft × 15 ft = 90 sq ft roll is not enough.

Natural Look on Slopes

1. Excavate shelves at different depths (marginal, deep).
2. Cover liner with geotextile underlayment.
3. Stack stones/rocks on shelves, mortared or dry-stacked.
4. Use gravel on bottom.
5. Plant marginals in baskets tucked among rocks.

Filtration

Even small ponds need a pump + filter (or bog filter). Plants alone insufficient if feeding fish. Pondmaster 1000 is a good starter filter. Place at deepest point; secure rocks on slopes with mortar (hide mortar).

Startup Sequence

1. Fill, dechlorinate, run pump/filter.
2. Add plants (submerged, marginal, floating).
3. Wait 2 weeks for biofilter to start.
4. Add snails, then fish gradually.