---
product_id: 532406096
title: "MS300 Marine Sealant, Window Sealer, Pond Sealer for Leaks Concrete Glass Metal, MS Polymer Adhesive 4x Stronger than Aquarium Silicone Caulking, Black Pond Liner Marine Adhesive Sealant, 300ml"
brand: "mypond"
price: "$89"
currency: NZD
in_stock: true
reviews_count: 13
category: "My Pond"
url: https://www.desertcart.nz/products/532406096-ms300-marine-sealant-window-sealer-pond-sealer-for-leaks-concrete
store_origin: NZ
region: New Zealand
---

# Waterproof & fish-safe 4x stronger than silicone Cures underwater in 24h MS300 Marine Sealant, Window Sealer, Pond Sealer for Leaks Concrete Glass Metal, MS Polymer Adhesive 4x Stronger than Aquarium Silicone Caulking, Black Pond Liner Marine Adhesive Sealant, 300ml

**Brand:** mypond
**Price:** $89
**Availability:** ✅ In Stock

## Summary

> Seal the deal with power and speed 💥🌊

## Quick Answers

- **What is this?** MS300 Marine Sealant, Window Sealer, Pond Sealer for Leaks Concrete Glass Metal, MS Polymer Adhesive 4x Stronger than Aquarium Silicone Caulking, Black Pond Liner Marine Adhesive Sealant, 300ml by mypond
- **How much does it cost?** $89 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.nz](https://www.desertcart.nz/products/532406096-ms300-marine-sealant-window-sealer-pond-sealer-for-leaks-concrete)

## Best For

- mypond enthusiasts

## Why This Product

- Trusted mypond brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **DIY-Pro Ready 🔧:** Heavy-duty hybrid polymer sealant designed for both professionals and passionate DIYers tackling pond and water feature projects.
- • **Versatile Bonding 🌐:** Adheres securely to concrete, glass, metal, wood, rubber, plastic, and more for all your sealing needs.
- • **Unmatched Strength 💪:** 4 times stronger than traditional aquarium silicone for durable, long-lasting seals.
- • **Rapid Underwater Cure ⏱️:** Sets fully underwater within 24 hours, speeding up your pond or aquarium repairs.
- • **Marine-Grade Reliability 🌊:** Waterproof and fish-safe formula ensures a healthy aquatic environment while sealing leaks.

## Overview

MyPond MS300 Marine Sealant is a 300ml black MS polymer adhesive that delivers 4x the strength of standard aquarium silicone. It cures underwater in just 24 hours, bonds to a wide range of materials, and is safe for fish and aquatic life—making it the ultimate solution for pond, aquarium, window, and marine leak repairs.

## Description

MyPond MS300 Marine Sealant, Window Sealer, Pond Sealer for Leaks Concrete Glass Metal, MS Polymer Adhesive 4x Stronger than Aquarium Silicone Caulking, Black Pond Liner Marine Adhesive Sealant, 300ml : desertcart.co.uk: Garden

Review: Very good, very messy - Quite awkward to work with, it sticks like mad to anything it touches, other than where you want it to stick or course. Cleaning it off your skin and nails afterwards is a challenge! But it cures very quickly even in cold weather and underwater and cured my leaky pond problems.
Review: Great product - Works well on butyl liner to butyl liner and stone alike.

## Features

- RELIABLE DIY POND REPAIR SOLUTION: MyPond heavy duty A+ grade hybrid adhesive or hybrid sealant make repairs and upgrades simple for DIY enthusiasts and professionals. This marine grade pond sealant helps you fix leaks and improve your pond or aquarium for long-lasting results. Our marine grade silicone sealant, waterproof hybrid polymer sealant works excellently as a pond leak sealer, fountain sealer, and even a koi pond sealer, ensuring durability for all your water features.
- STRONGER THAN TRADITIONAL SILICONE: Our pond sealant fish safe is 4 times stronger than regular waterproof silicone sealant, providing superior sealing power for your pond and water features. Whether you need a pond sealer, pond leak sealer, or aquarium MS polymer sealant, our marine grade MS polymer adhesive sealant ensures fewer repairs and long-lasting protection. It also works well as a glass sealant, window sealant, pond window sealer, or even a gutter sealant for rain gutters.
- FAST CURING UNDERWATER: This waterproof MS polymer glue cures underwater in just 24 hours, saving you time and hassle on your DIY pond projects. Ideal for use as a pond sealer, pond leak sealer, or underwater sealant, it provides quick, reliable results. Whether you're sealing a fish pond or repairing an aquarium, this aquarium silicone black marine silicone, pond sealer for leaks ensures your projects are completed efficiently, with lasting results.
- VERSATILE AND FLEXIBLE BONDING: Our MS polymer adhesive bonds securely to materials like concrete, stone, wood, glass, metal, rubber, plastic, and fiberglass. This makes it a versatile choice for a wide range of projects, including as an aquarium sealant, aquarium caulk, window crack repair and marine sealant for all water-based applications. It works as a fish pond sealant, fountain sealer, and even for koi pond repairs.
- FISH-SAFE FORMULA FOR AQUATIC LIFE: Ensure the safety of your aquatic life with our pond sealer safe for fish. This fish pond sealant is great for maintaining a healthy, natural environment in your pond. Whether you're using it as a pond leak sealer, marine grade MS polymer sealant, aquarium MS polymer sealant, or reptile safe sealant, our MyPond MS300 sealant, marine caulking keeps your water feature safe for fish, plants, and reptiles alike.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0C2VBJ2BL |
| Batteries Required? | No |
| Batteries included? | No |
| Best Sellers Rank | 1,614 in Garden ( See Top 100 in Garden ) 4 in Pond Care & Water Treatment |
| Customer Reviews | 4.4 4.4 out of 5 stars (278) |
| Date First Available | 16 Oct. 2023 |
| Item Weight | 450 g |
| Manufacturer | MyPond |
| Manufacturer reference | Ms-300 |
| Package Dimensions | 23.9 x 14.4 x 10.5 cm; 450 g |
| Part number | Ms-300 |
| Style | Compact |

## Product Details

- **Brand:** MyPond
- **Item form:** Liquid
- **Style:** Compact
- **Unit count:** 300.0 millilitre
- **Water resistance level:** Waterproof

## Images

![MS300 Marine Sealant, Window Sealer, Pond Sealer for Leaks Concrete Glass Metal, MS Polymer Adhesive 4x Stronger than Aquarium Silicone Caulking, Black Pond Liner Marine Adhesive Sealant, 300ml - Image 1](https://m.media-amazon.com/images/I/61vFY6Ju-xL.jpg)

## Questions & Answers

**Q: Can this sealant be applied to a pond or aquarium while it’s filled with water, or must the surface be dry first?**
A: It can be applied directly to wet or submerged areas. This underwater sealant fully cures in 24 hours and becomes a pond sealant fish safe once dry, making it ideal for aquariums, koi ponds, fountains, and other aquatic environments.

**Q: Will the sealant bond effectively to a wide range of surfaces like wood, metal, plastic, stone, and glass?**
A: Yes, this hybrid polymer sealant offers strong, flexible adhesion to glass, stone, plastic, and more. It also performs well as a glass sealant, ensuring waterproof protection and long-term durability on a variety of indoor and outdoor surfaces.

**Q: Once the sealant is fully cured, is it safe for all aquatic life, including koi fish, turtles, and amphibians?**
A: Once cured, it’s completely non-toxic. It works as a koi pond sealer and pond sealer safe for fish, reptiles, and amphibians. Ideal for tanks, ponds, or habitats where the safety of aquatic animals and plants is critical and long-lasting.

**Q: Is this suitable for sealing bathrooms, kitchen sinks, or windows where strong waterproofing is essential?**
A: Absolutely. It works as a window sealer and waterproof silicone for high-moisture areas like showers, tiles, sinks, and windows. It delivers long-lasting protection, prevents mold buildup, and provides a clean, nearly invisible finish.

**Q: Will this product stay flexible after curing, especially when exposed to outdoor temperatures and movement?**
A: Yes, it remains permanently flexible after curing. This adhesive sealant resists cracking or shrinking, even in changing temperatures. Ideal as a floor sealant and for roofs, walls, garden features, and high-movement outdoor joints.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Very good, very messy
*by G***A on 20 March 2025*

Quite awkward to work with, it sticks like mad to anything it touches, other than where you want it to stick or course. Cleaning it off your skin and nails afterwards is a challenge! But it cures very quickly even in cold weather and underwater and cured my leaky pond problems.

### ⭐⭐⭐⭐⭐ Great product
*by D***Y on 15 September 2025*

Works well on butyl liner to butyl liner and stone alike.

### ⭐⭐⭐⭐ Excellent for pond liner repairs
*by S***S on 15 March 2025*

Great product. Really does what you hope it will. It is very good at fixing pond liners BUT I have to take off a star because No matter how careful you are it will get on something that you don't want it too. And anything that touches that, or touches the thing that touched that And it's impossible to get off.

## Frequently Bought Together

- MyPond MS300 Marine Sealant, Window Sealer, Pond Sealer for Leaks Concrete Glass Metal, MS Polymer Adhesive 4x Stronger than Aquarium Silicone Caulking, Black Pond Liner Marine Adhesive Sealant, 300ml
- Gorilla Waterproof Patch & Seal Tape Black 3m
- Double Sided Butyl Tape Used for Membrane Jointing, Waterproofing, Pond Liner Repair (50MM X 1.5MM X 10M)

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*Product available on Desertcart New Zealand*
*Store origin: NZ*
*Last updated: 2026-02-12*