Protect your pond liner from rips and tears from stones, rocks and other sharp edges with the Pisces pond underlay. Made from high-quality geotextile fabric, the underlay creates a strong layer that helps prevent damage.Unlike other standard fleece materials, the polypropylene is designed to withstand contact with the ground and water without rotting or breaking down, making it last for years.Although ideal for use beneath pond liners, this versatile material can also be placed on top of the liner when using decorative substrates such as gravel. Its strength and flexibility make it easy to install, cut to size, and shape around your pond.Available in lengths of up to 20 metres, the underlay can be trimmed to suit your exact pond layout, making installation quick and straightforward.How to work out how much underlay you need: Underlay Length Required: Max Pond Length + 2x Maximum Pond Depth Underlay Width Required: Max Pond Width + 2x Maximum Pond DepthOnce you have worked out how much liner you require, add 50cm to both the length and width to allow for some overlap to help secure the liner in place.For example: If you have a pond size of 3m x 4m x 2m (L x W x D): Underlay Length = 3m + (2x 2m Depth = 4m) + 50cm Overlap = 7.5mUnderlay Width = 4m + (2x 2m Depth = 4m) + 50cm Overlap = 8.5m Total Underlay Required: 7.5 x 8.5m Chosen length is dispatched from us in one continuous piece 2m x 1mGrams Per Square Metre: 250 gsm.