{"product_id":"pondlinersco-clear-pond-sealer","title":"PondLinersco Clear Pond Sealer | Waterproof Concrete \u0026 Render | Fish Safe Formula","description":"\u003ch2\u003ePondLinersco Clear Pond Sealer UK — Waterproof Concrete \u0026amp; Render | Fish Safe Formula | Stops Lime Leaching\u003c\/h2\u003e\n\u003cp\u003eNew concrete, mortar, and render release alkaline lime compounds that are harmful — even lethal — to pond fish and aquatic wildlife. Our \u003cstrong\u003eClear Pond Sealer\u003c\/strong\u003e is the essential protective coating that creates a safe barrier between concrete surfaces and pond water, making any concrete pond feature immediately fish-safe after application and curing.\u003c\/p\u003e\n\u003cdiv class=\"plx-keyfacts\" style=\"border:1px solid #d7e3d7;border-left:4px solid #2d6a2d;border-radius:6px;padding:16px 20px;margin:20px 0;background:#f6faf6;\"\u003e\n\u003ch3 style=\"margin-top:0;\"\u003ePondLinersco Clear Pond Sealer: Key Facts\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct:\u003c\/strong\u003e PondLinersco Clear Pond Sealer\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e single-pack, moisture-curing polyurethane\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCoverage:\u003c\/strong\u003e 550g per m² for the full system, so a 1kg tin seals about 1.8m²\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCoats:\u003c\/strong\u003e 3 coats\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRecoat:\u003c\/strong\u003e every 60 to 90 minutes; never leave more than 4 hours between coats\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConditions:\u003c\/strong\u003e can be applied down to 0°C and in high humidity, onto clean, porous render that may be slightly damp\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSizes:\u003c\/strong\u003e 1kg, 2.5kg and 5kg\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNot compatible with:\u003c\/strong\u003e PVC, butyl rubber or bitumen, so do not use it on pond liners\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSold by:\u003c\/strong\u003e PondLinersco.co.uk (Express Matting Services Ltd, Burnley, Lancashire, UK)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cp style=\"margin:0 0 20px;\"\u003e\u003ca href=\"\/pages\/pond-sealer-calculator\" style=\"display:inline-block;background:#2d6a2d;color:#fff;padding:12px 20px;border-radius:6px;font-weight:700;text-decoration:none;\"\u003eHow much sealer do I need? Use the free pond sealer calculator →\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003eWhether you're finishing the coping edge of a new liner pond, sealing a rendered concrete shell, waterproofing brick edging, or reinforcing existing concrete pond walls, our fish-safe pond sealer delivers professional results accessible to any DIY pond builder. It dries clear, leaving no visual impact while providing complete chemical protection.\u003c\/p\u003e\n\u003ch3\u003eFull Technical Specifications\u003c\/h3\u003e\n\u003ctable border=\"1\" cellpadding=\"6\" cellspacing=\"0\"\u003e\n\u003ctr\u003e\n\u003cth\u003eProperty\u003c\/th\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eSingle-pack moisture-curing polyurethane\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormulation\u003c\/td\u003e\n\u003ctd\u003ePolyurethane resin that cures using moisture in the air and the substrate; no primer needed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFish Safe\u003c\/td\u003e\n\u003ctd\u003e✅ Yes — certified safe when fully cured\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoverage\u003c\/td\u003e\n\u003ctd\u003e550g per m² for the full 3-coat system (about 1.8m² per 1kg)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDry Time\u003c\/td\u003e\n\u003ctd\u003eCan be walked on in 60–90 minutes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRe-coating\u003c\/td\u003e\n\u003ctd\u003eEvery 60–90 minutes; no more than 4 hours between coats\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTemperature\u003c\/td\u003e\n\u003ctd\u003eCan be applied down to 0°C, including in poor weather and high humidity\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNumber of Coats\u003c\/td\u003e\n\u003ctd\u003e3 coats\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable Surfaces\u003c\/td\u003e\n\u003ctd\u003eConcrete, render, brick, mortar, stone\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNot Compatible With\u003c\/td\u003e\n\u003ctd\u003ePVC, butyl rubber, bitumen\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWaterproofing\u003c\/td\u003e\n\u003ctd\u003eExcellent — forms continuous impermeable membrane\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eColour When Dry\u003c\/td\u003e\n\u003ctd\u003eCompletely clear — invisible finish\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eClean-up\u003c\/td\u003e\n\u003ctd\u003eCellulose thinners (turpentine and white spirit are unsuitable)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eShelf Life\u003c\/td\u003e\n\u003ctd\u003eUp to 2 years unopened; use soon after opening, as it cures with moisture\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSafety\u003c\/td\u003e\n\u003ctd\u003eFlammable and irritant: wear gloves and eye protection, avoid ignition sources and do not breathe the vapour\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\u003ch3\u003e5 Use Cases for Pond Sealer\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e🏗️ \u003cstrong\u003eNew Concrete Pond Edges\u003c\/strong\u003e — Sealing freshly laid concrete coping stones and mortar beds before pond filling — prevents lime leaching during the critical curing period\u003c\/li\u003e\n\u003cli\u003e🧱 \u003cstrong\u003eRendered Concrete Pond Shells\u003c\/strong\u003e — Creating a complete fish-safe waterproof membrane on rendered concrete ponds, both new construction and renovation\u003c\/li\u003e\n\u003cli\u003e🌊 \u003cstrong\u003eBrick-Edged Pond Features\u003c\/strong\u003e — Sealing brick and mortar joints in formal raised pond walls to prevent chemical leaching and water seepage\u003c\/li\u003e\n\u003cli\u003e🩹 \u003cstrong\u003ePond Repair and Renovation\u003c\/strong\u003e — Restoring existing concrete ponds: repair and fill any cracks or damaged render first, then seal with three coats\u003c\/li\u003e\n\u003cli\u003e⚠️ \u003cstrong\u003eNot for Pond Liners\u003c\/strong\u003e — This sealer is not compatible with PVC, butyl rubber or bitumen, so never apply it to a pond liner or liner joins. For liner repairs use \u003ca href=\"\/products\/butyl-pond-liner-joining-tape-uk-double-sided-50mm-x-1m-waterproof-repair\"\u003eliner joining tape\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eStep-by-Step Application Guide\u003c\/h3\u003e\n\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrepare the surface\u003c\/strong\u003e — Clean all concrete, mortar, and stone surfaces thoroughly. Remove loose material, moss, algae, and existing coatings. Repair and fill cracks. The render must be porous so the first coat can grip: it can be slightly damp, but highly trowelled, glassy surfaces are not advised\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFirst coat application\u003c\/strong\u003e — Apply the first coat by brush, working it into all crevices, joins, and corners. Avoid thick coats\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAllow to dry\u003c\/strong\u003e — Recoat after 60–90 minutes. Do not leave more than 4 hours between coats\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSecond and third coats\u003c\/strong\u003e — Apply the second and third coats the same way (later coats may be thinned and sprayed)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCure and fill\u003c\/strong\u003e — Allow the final coat to cure fully before filling the pond (24 hours is a sensible minimum). For maximum fish safety, fill with water, leave 24 hours, completely empty, then refill before introducing fish\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch3\u003eWhy Pond Sealer Is Essential\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eLime toxicity — uncured concrete releases highly alkaline lime that kills fish and amphibians rapidly\u003c\/li\u003e\n\u003cli\u003eLong-term pH stability — sealed concrete maintains stable water pH\u003c\/li\u003e\n\u003cli\u003eWaterproofing — prevents water seeping through porous concrete and mortar\u003c\/li\u003e\n\u003cli\u003eEasy application — brush on, no primer needed, and it can be applied in cold, damp weather\u003c\/li\u003e\n\u003cli\u003eInvisible finish — clear formulation preserves the natural appearance of stone and concrete\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e✅ Trust \u0026amp; Guarantee\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e✅ Fish Safe Certified — Tested and certified safe for fish and aquatic wildlife when cured\u003c\/li\u003e\n\u003cli\u003e✅ Free UK Delivery — All mainland UK orders delivered free\u003c\/li\u003e\n\u003cli\u003e✅ Professional Formula — Same formulation used by professional pond contractors\u003c\/li\u003e\n\u003cli\u003e✅ Expert Advice Available — Application advice from our pond construction specialists\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eQ: How long after applying pond sealer can I introduce fish?\u003c\/strong\u003e\u003cbr\u003eA: Allow minimum 24 hours after the final coat before filling the pond. Once filled, change the water once after 24 hours, then it is safe to introduce fish. Test pH (should be 7.0–8.0) before introducing fish.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQ: How many coats of pond sealer do I need?\u003c\/strong\u003e\u003cbr\u003eA: Three coats, recoating every 60–90 minutes and never leaving more than 4 hours between coats.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Can I use pond sealer on an existing pond with fish in it?\u003c\/strong\u003e\u003cbr\u003eA: No. Fish must be removed to a holding vessel before application. Once the sealer is fully cured, the water changed, and pH confirmed stable, fish can be returned.\u003c\/p\u003e\n\u003ch3\u003eHow Much Pond Sealer Do I Need?\u003c\/h3\u003e\n\u003cp\u003eWork out the inside area of the pond (the floor plus every wall), then multiply by 0.55kg per m² for the full three-coat system:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSealer needed (kg) = (floor area + wall area) × 0.55\u003c\/strong\u003e\u003c\/p\u003e\n\u003ctable border=\"1\" cellpadding=\"6\" cellspacing=\"0\"\u003e\n\u003ctr\u003e\n\u003cth\u003ePond (length × width × depth)\u003c\/th\u003e\n\u003cth\u003eFloor + walls\u003c\/th\u003e\n\u003cth\u003eSealer needed\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e2m × 1.5m × 0.6m\u003c\/td\u003e\n\u003ctd\u003e3m² + 4.2m² = 7.2m²\u003c\/td\u003e\n\u003ctd\u003eabout 4kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e3m × 2m × 1m\u003c\/td\u003e\n\u003ctd\u003e6m² + 10m² = 16m²\u003c\/td\u003e\n\u003ctd\u003eabout 8.8kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e4m × 3m × 1.2m\u003c\/td\u003e\n\u003ctd\u003e12m² + 16.8m² = 28.8m²\u003c\/td\u003e\n\u003ctd\u003eabout 15.8kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\u003cp\u003eOur \u003ca href=\"\/pages\/pond-sealer-calculator\"\u003epond sealer calculator\u003c\/a\u003e works this out for any pond and picks the cheapest mix of tins.\u003c\/p\u003e\n\u003ch3\u003ePondLinersco Clear Pond Sealer: Questions Answered\u003c\/h3\u003e\n\u003ch4\u003eCan I use this sealer on a pond liner?\u003c\/h4\u003e\n\u003cp\u003eNo. It is not compatible with PVC, butyl rubber or bitumen. Use it on concrete, render, brick and porous stone only.\u003c\/p\u003e\n\u003ch4\u003eCan I apply it in cold or damp weather?\u003c\/h4\u003e\n\u003cp\u003eYes. It cures using moisture in the air and can be applied down to 0°C and in high humidity. The render should still be porous enough for the first coat to grip.\u003c\/p\u003e\n\u003ch4\u003eHow long between coats?\u003c\/h4\u003e\n\u003cp\u003eRecoat after 60–90 minutes and do not leave more than 4 hours between coats, so each coat bonds to the last.\u003c\/p\u003e\n\u003ch4\u003eHow much does a 1kg tin cover?\u003c\/h4\u003e\n\u003cp\u003eAbout 1.8m² with the full three-coat system (550g per m²).\u003c\/p\u003e\n\u003ch3\u003eHelpful Guides\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"\/pages\/pond-sealer-calculator\"\u003ePond sealer calculator\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/pages\/how-to-seal-concrete-pond\"\u003eHow to seal a concrete pond\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/blogs\/news\/concrete-pond-vs-pond-liner-uk\"\u003eConcrete pond vs pond liner\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n","brand":"PondLiners Co","offers":[{"title":"Clear - 1KG","offer_id":55322639532380,"sku":"SEALER-CLEAR-Clear-1KG","price":59.99,"currency_code":"GBP","in_stock":true},{"title":"Clear - 2.5KG","offer_id":55322639565148,"sku":"SEALER-CLEAR-Clear-25KG","price":119.99,"currency_code":"GBP","in_stock":true},{"title":"Clear - 5KG","offer_id":55322639597916,"sku":"SEALER-CLEAR-Clear-5KG","price":199.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0889\/2035\/9260\/files\/pondlinersco-clear-pond-sealer.jpg?v=1791013230","url":"https:\/\/www.pondlinersco.co.uk\/products\/pondlinersco-clear-pond-sealer","provider":"PondLinersco.co.uk","version":"1.0","type":"link"}