{"product_id":"bioscape-coral-rubble-20-50mm-diameter","title":"Bioscape Coral Rubble 20-50mm Diameter","description":"\u003cp\u003e\u003cstrong\u003eChunks of real coral and aragonite that hold your tank's pH and hardness steady.\u003c\/strong\u003e Bioscape Coral Rubble is 20–50mm pieces of coral skeleton and aragonite, sized for building reef structure, sump and refugium media beds, or a buffering base layer under African cichlid rockwork.\u003c\/p\u003e\u003ch3\u003eKey features\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCoral and aragonite blend\u003c\/strong\u003e — calcium carbonate media that slowly dissolves to release calcium and carbonate into the water column.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003epH and alkalinity buffer\u003c\/strong\u003e — helps hold water parameters stable rather than letting them drift acidic over time, which matters most in marine and African cichlid tanks.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh surface area\u003c\/strong\u003e — the irregular, chunky pieces give beneficial bacteria plenty of room to colonise, adding biological filtration wherever the rubble sits.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e20–50mm piece size\u003c\/strong\u003e — large enough to use as structural reef base rock, sump media or a coarse foundation layer, rather than a fine substrate.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003ctable\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eComposition\u003c\/th\u003e\n\u003ctd\u003eCoral skeleton and aragonite\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePiece size\u003c\/th\u003e\n\u003ctd\u003e20–50mm diameter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eColour\u003c\/th\u003e\n\u003ctd\u003eNatural neutral tones\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFunction\u003c\/th\u003e\n\u003ctd\u003epH\/alkalinity buffer, biological filtration media, reef and cichlid aquascaping\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e\u003ch3\u003eWhich size do I need?\u003c\/h3\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eVariant\u003c\/th\u003e\n\u003cth\u003eSKU\u003c\/th\u003e\n\u003cth\u003ePrice\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e5kg bag\u003c\/td\u003e\n\u003ctd\u003eCOR03\u003c\/td\u003e\n\u003ctd\u003e$45.95\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e10kg bag\u003c\/td\u003e\n\u003ctd\u003eCOR04\u003c\/td\u003e\n\u003ctd\u003e$79.95\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003cp\u003eBioscape has not published a coverage or depth figure per kilogram for this rubble, so we can't state how many kilograms you'll need for a given tank footprint here — as a rough real-world guide, rubble this size is normally used as a partial structural layer or sump\/refugium media rather than a full substrate bed, so actual quantity depends heavily on your layout.\u003c\/p\u003e\u003ch3\u003eCoral Rubble vs Coral Sand — which do I need?\u003c\/h3\u003e\u003cp\u003eRubble's larger 20–50mm pieces suit structural jobs — reef rockwork bases, sump and refugium media, or a coarse layer under cichlid rock piles. Bioscape Coral Sand's fine 1mm grain is what you want for an even substrate bed that sand-sifting fish and gobies can actually move through. Many reef and cichlid setups use both: sand as the visible substrate, rubble hidden in the sump or refugium as extra buffering media.\u003c\/p\u003e\u003ch3\u003eSuitable for, and not suitable for\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSuitable for:\u003c\/strong\u003e marine and reef aquariums, African cichlid tanks, sumps and refugiums wanting extra calcium\/alkalinity buffering.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNot suitable for:\u003c\/strong\u003e soft or acidic-water setups — South American cichlids, most planted tanks and blackwater biotopes — where a rising pH and hardness from dissolving carbonate is the opposite of what you want.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eCare and maintenance\u003c\/h3\u003e\u003cp\u003eRinse before adding to remove dust from bagging and transit. Buffering capacity reduces as the rubble dissolves over years of use; test alkalinity periodically in heavily stocked reef systems rather than assuming it buffers forever.\u003c\/p\u003e\u003ch3\u003eWarranty and delivery\u003c\/h3\u003e\u003cp\u003eEach piece is a natural product — size, shape and exact colour vary bag to bag, and photos are representative rather than exact. Any fault on arrival is covered under your consumer guarantee rights under Australian Consumer Law.\u003c\/p\u003e\u003ch3\u003eCommon questions\u003c\/h3\u003e\u003ch4\u003eWill this raise my pH too high?\u003c\/h4\u003e\u003cp\u003eIt buffers pH upward and holds it stable rather than pushing it indefinitely higher — this is exactly what marine and African cichlid tanks are meant to run at, but it's the wrong media for soft or acidic-water species.\u003c\/p\u003e\u003ch4\u003eHow much do I need for my tank?\u003c\/h4\u003e\u003cp\u003eBioscape hasn't published a coverage figure, and rubble is typically used as a partial structural or sump layer rather than a full substrate bed, so quantity depends on your specific layout — buy the smaller 5kg bag first if you're unsure and top up.\u003c\/p\u003e\u003ch4\u003eCan I mix this with regular gravel?\u003c\/h4\u003e\u003cp\u003eYes — rubble is commonly mixed with or layered under other substrates for extra buffering, though the buffering effect scales with how much rubble is actually present.\u003c\/p\u003e","brand":"Bioscape","offers":[{"title":"5kg","offer_id":55293071524131,"sku":"COR03","price":45.95,"currency_code":"AUD","in_stock":false},{"title":"10kg","offer_id":55335001424163,"sku":"COR04","price":79.95,"currency_code":"AUD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0972\/7236\/5347\/files\/bioscape-coral-rubble-5kg.jpg?v=1783990087","url":"https:\/\/nicksaquariumoceanariumterrarium.com.au\/products\/bioscape-coral-rubble-20-50mm-diameter","provider":"Nicks Aquarium Oceanarium Terrarium","version":"1.0","type":"link"}