{"product_id":"seachem-onyx-sand-7-7-lb","title":"Seachem Onyx Sand 7.7 lb Planted Aquarium Substrate","description":"\u003cp\u003e\u003cstrong\u003eSeachem Onyx Sand\u003c\/strong\u003e is a premium dark gray to black sand substrate designed for freshwater planted aquariums and aquariums with species that prefer higher pH and hardness. Its natural dark coloration creates a bold aquascape look while helping plants, fish, shrimp, rocks, and driftwood stand out beautifully.\u003c\/p\u003e\n\u003cp\u003eOnyx Sand is porous, long-lasting, and carbonate-rich, making it a strong choice for planted tanks, hard water aquariums, African cichlid setups, livebearer tanks, and aquascaped freshwater displays. Because it may raise pH and hardness, it is especially useful for aquariums where a more alkaline environment is desired.\u003c\/p\u003e\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eGreat for Planted Aquariums:\u003c\/strong\u003e Porous sand substrate provides a stable base for rooted aquatic plants.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCarbonate-Rich Formula:\u003c\/strong\u003e May help buffer pH and hardness for species that prefer alkaline water.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNatural Dark Color:\u003c\/strong\u003e Dark gray to black tones create strong contrast with plants, fish, shrimp, and decor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLong-Lasting Substrate:\u003c\/strong\u003e Does not break down or require routine replacement over time.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHard Water Friendly:\u003c\/strong\u003e Useful for planted aquariums, African cichlids, livebearers, and other harder-water setups.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUse Alone or Mixed:\u003c\/strong\u003e Can be used as the main substrate or blended with other aquarium sands and gravels.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e7.7 lb Bag:\u003c\/strong\u003e Convenient size for nano tanks, small aquariums, accent areas, or deeper planting zones.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eProduct Details\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Seachem\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct:\u003c\/strong\u003e Onyx Sand\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSize:\u003c\/strong\u003e 7.7 lb bag\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Porous planted aquarium sand substrate\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e Dark gray to black\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWater Chemistry:\u003c\/strong\u003e Carbonate-rich; may raise pH and hardness\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBest For:\u003c\/strong\u003e Planted tanks, hard water aquariums, African cichlids, livebearers, aquascapes, and root-feeding plants\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eBest For\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eFreshwater planted aquariums\u003c\/li\u003e\n\u003cli\u003eHard water aquarium setups\u003c\/li\u003e\n\u003cli\u003eAfrican cichlid aquariums\u003c\/li\u003e\n\u003cli\u003eLivebearer tanks\u003c\/li\u003e\n\u003cli\u003eRoot-feeding aquarium plants\u003c\/li\u003e\n\u003cli\u003eDark substrate aquascapes\u003c\/li\u003e\n\u003cli\u003eCommunity aquariums with compatible water needs\u003c\/li\u003e\n\u003cli\u003eAccent areas or deeper planting zones\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003ePlant Benefits\u003c\/h3\u003e\n\u003cp\u003eSeachem Onyx Sand provides a stable porous substrate base for rooted aquarium plants. Its fine texture helps plants anchor while creating a clean, natural-looking substrate bed.\u003c\/p\u003e\n\u003cp\u003eFor demanding plants or heavy root feeders, Onyx Sand works best when paired with root tabs, liquid fertilizers, proper lighting, and regular aquarium maintenance.\u003c\/p\u003e\n\u003ch3\u003eWater Chemistry Note\u003c\/h3\u003e\n\u003cp\u003eUnlike neutral substrates, Seachem Onyx Sand is carbonate-rich and may slightly increase aquarium pH and hardness. This makes it a good option for planted tanks and freshwater species that prefer harder, more alkaline water.\u003c\/p\u003e\n\u003cp\u003eFor soft-water fish or shrimp that require lower pH and very soft water, test your water regularly and confirm that Onyx Sand fits the needs of your livestock.\u003c\/p\u003e\n\u003ch3\u003eUsage Tips\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eRinse well before use to help remove dust and fine particles.\u003c\/li\u003e\n\u003cli\u003eAdd water slowly over a plate, bowl, or plastic bag to avoid disturbing the substrate.\u003c\/li\u003e\n\u003cli\u003eUse a deeper layer in areas where heavy planting is planned.\u003c\/li\u003e\n\u003cli\u003ePair with root tabs or liquid fertilizers for nutrient-demanding plants.\u003c\/li\u003e\n\u003cli\u003eTest pH and hardness after setup, especially when keeping sensitive fish or shrimp.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCoverage Guide\u003c\/h3\u003e\n\u003cp\u003eCoverage will vary based on tank dimensions, desired substrate depth, and aquascaping style. One 7.7 lb bag is commonly used for nano aquariums, small planted tanks, accent sections, or deeper planting zones in larger aquascapes.\u003c\/p\u003e\n\u003cp\u003eFor larger aquariums or deeper substrate beds, multiple bags may be needed.\u003c\/p\u003e\n\u003ch3\u003eWhy Choose Seachem Onyx Sand?\u003c\/h3\u003e\n\u003cp\u003eSeachem Onyx Sand is a strong choice for aquarists who want a dark planted tank substrate that also supports harder-water aquarium setups. Its dark color adds contrast, while its carbonate-rich composition can help maintain conditions preferred by certain plants and freshwater species.\u003c\/p\u003e\n\u003cp\u003eIt is especially useful for aquascapes with plants, rocks, African cichlids, livebearers, and other freshwater aquarium layouts where a slightly higher pH and hardness are desired.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eWill Seachem Onyx Sand raise pH?\u003c\/h4\u003e\n\u003cp\u003eYes. Onyx Sand is carbonate-rich and may slightly increase pH and hardness, making it a good choice for plants and freshwater species that prefer more alkaline conditions.\u003c\/p\u003e\n\u003ch4\u003eDo I need to rinse Onyx Sand before use?\u003c\/h4\u003e\n\u003cp\u003eYes. Rinse well before adding it to the aquarium to help remove dust and reduce initial cloudiness.\u003c\/p\u003e\n\u003ch4\u003eCan Seachem Onyx Sand be used with bottom-dwelling fish?\u003c\/h4\u003e\n\u003cp\u003eYes. The fine grain is suitable for many bottom-dwelling freshwater fish when rinsed and used properly. Always match the substrate and water parameters to the needs of the species being kept.\u003c\/p\u003e\n\u003ch4\u003eIs Onyx Sand safe for shrimp tanks?\u003c\/h4\u003e\n\u003cp\u003eYes, but it may buffer pH and hardness higher than neutral. It is best for shrimp species that tolerate or prefer harder, more alkaline water.\u003c\/p\u003e\n\u003ch4\u003eCan Onyx Sand be used in planted aquariums?\u003c\/h4\u003e\n\u003cp\u003eYes. Onyx Sand is designed for planted aquariums and provides a stable base for rooted plants. Root tabs may be helpful for heavy root-feeding plants.\u003c\/p\u003e\n\u003ch4\u003eDoes Onyx Sand need to be replaced?\u003c\/h4\u003e\n\u003cp\u003eNo. Onyx Sand is long-lasting and does not break down or require routine replacement.\u003c\/p\u003e\n\u003ch3\u003eAvailable at Tropical Treasures Wyo\u003c\/h3\u003e\n\u003cp\u003eShop \u003cstrong\u003eSeachem Onyx Sand 7.7 lb Planted Aquarium Substrate\u003c\/strong\u003e online or in-store at Tropical Treasures Wyo in Cheyenne, Wyoming. This dark carbonate-rich aquarium substrate is a great choice for planted tanks, hard water aquariums, African cichlid setups, livebearer tanks, and natural freshwater aquascapes.\u003c\/p\u003e","brand":"Tropical Treasures Wyo LLC","offers":[{"title":"Default Title","offer_id":51990994059477,"sku":null,"price":15.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0670\/4545\/8133\/files\/SC35030-2T.png?v=1757162744","url":"https:\/\/tropicaltreasureswyo.com\/products\/seachem-onyx-sand-7-7-lb","provider":"Tropical Treasures Wyo LLC","version":"1.0","type":"link"}