A leaking pond loses water through the soil of its floor and walls. Sodium bentonite swells when wet and fills those pores, forming a layer that water cannot easily pass. It is used to seal farm ponds, irrigation reservoirs, canals, lagoons and aquaculture ponds.
Technical Specifications
Sodium vs calcium bentonite: which do you need?
Sodium bentonite swells many times its size in water and forms a seal or gel; calcium bentonite barely swells and is valued as an absorbent carrier. That one property decides who buys each grade. This page covers sodium bentonite.
| Sodium bentonite | Calcium bentonite | |
|---|---|---|
| Key behaviour | Swells strongly, forms gel and low-permeability seal | Low swell, high absorbency, holds liquids |
| Granule uses | Pond, lake and canal sealing; borehole and well annulus sealing; landfill and geosynthetic clay liners; clumping cat litter | Carrier granules for pesticides, bio-fertilizers and micronutrients (10x20, 16x35 mesh); soil conditioner; non-clumping litter; oil and spill absorbent |
| Powder uses | Drilling mud (oil, water well, HDD); iron ore pelletizing binder (75 micron); foundry green sand; sulphur-bentonite fertilizer (90:10); diaphragm wall and piling slurry; wine and juice fining | Fertilizer granulation binder; bleaching earth after acid activation (edible oil refining); ceramics; cosmetics and face packs |
| Main buyers | Drilling contractors, steel and pellet plants, foundries, cat litter brands, pond and landfill contractors, GCL makers, sulphur fertilizer makers | Agrochemical and bio-fertilizer formulators, NPK plants, oil refineries, ceramic and cosmetic makers |
| Tests buyers ask for | Swell index (ml/2g), gel/viscosity, fluid loss, moisture, mesh | Absorption (oil/water), crush strength, mesh, moisture, pH, dust |
Much “sodium bentonite” sold in India is calcium bentonite treated with soda ash (activated sodium). Ask for the swell index (ml/2g) and whether a grade is natural or activated before you order.
Read the full guide: sodium vs calcium bentonite powderRequest a Quote
Share your grade, quantity, and delivery location. We reply with a quotation for bulk orders.
Quick Product Inquiry
For: Sodium Bentonite for Pond Sealing
Who this is for
Pond builders and landscaping contractors, irrigation departments, farmers with leaking farm ponds, and aquaculture operators lining shrimp and fish ponds. If you hire a contractor, give them the swell index and the application rate we quote.
How bentonite seals a pond
Two methods are common. In the mixed-layer method, bentonite is spread over the dry pond floor and mixed into the top soil, then compacted. In the surface method, bentonite is spread on the water surface of a filled pond and sinks to seal the leaks. The right one depends on the soil: sandy soils usually need more bentonite than clay-rich ones.
Application rates depend on soil and on the bentonite itself, so we do not publish a single figure. Ask for a rate based on your soil test and the swell index of the batch.
Related Products
View full categoryFrequently Asked Questions
Can calcium bentonite seal a pond?
Poorly. Calcium bentonite swells little. Use a sodium bentonite with a stated swell index.
How much bentonite does a pond need?
It depends on the soil and the grade. Share the pond area, depth and soil type and we will quote a rate once the swell index is confirmed: [TBC: recommended kg per m² by soil type].
Is bentonite safe for fish ponds?
Natural bentonite is widely used to seal aquaculture ponds. Tell us the species and the pond so we can agree the grade; we make no health claims.