How do we Fibreglass line Ponds??
Having been carrying out Fibreglass Linings to Koi Ponds for over 40 years my chosen method is to prime the rendered surface, apply 600gm matting, thoroughly soak with Polyester Resin and roll using lambs wool rollers, when cured apply a resin colour coat, when this is cured using orbital sanders sand all surface areas smooth.
We then apply a topcoat consisting of special chemicals that stop the Polyester Resins from leaching harmful chemicals that can harm your fish.
Please allow to fully cure for 7 days, wash all areas of pond, clean water from Pond and fill.