Common aquarium gravel is a good fail-safe as a substrate material. It is made of crushed quartz and provides a suitable surface for beneficial bacteria and is agreeable to most bottom-dwellers. Fresh water aquarium sand sold in most aquarium supply stores can also be used. Unlike sand found in nature, this sand is sterilized prior to being sold. Sandblasting sand and playground sand can also be used. Sand of course is abrasive, if the aquarium is made of acrylic, as opposed to glass, it should be taken into account that sand may contribute to scratching. Some species of fish, such as feather fins, may actually prefer sand in a freshwater aquarium as opposed to gravel.
Freshwater Sand Sifter? - Aquarium Advice - Aquarium Forum Community
Now what kind of organisms help with NNR? In saltwater, there are many types of tube worms, snails, and other bugs that help with the slow exchange of water through the bed. In freshwater, there are snails (Malaysian Livebearing Snail), fish like cory cats and loaches, worms (California Black Worms/Tubifex worms), and other bugs. As you can see the sand bed is a very diverse eco-system with all organisms interdependent of one another to keep the aquarium water chemistry safe for your aquarium inhabitants.
live sand in freshwater. - Aquarium Advice - Aquarium Forum Community
The photo to the left shows a deep sand bed in a saltwater aquarium. Notice the tubes in the sand. These tubes are formed by spaghetti worms that filter the water column. When these worms move up and down the tube they help exchange water in the sand bed. The photo on the right shows a Corydoras bilineatus (San Juan Cory) and a Malaysian Livebearing Snail in a freshwater aquarium with #60 natural sand as a substrate.
Freshwater Aquarium Sand, Gravel, or Rocks
No, Estes Marine Sand is inert and will not alter any chemistry in any way. This makes it an ideal sand for any tank (freshwater, saltwater, reef, planted, etc.). Unlike other silica based sands it won’t ever add silicates (which can cause brown algae problems) because of the ceramic coating. For certain tanks where a high pH and hard water are appropriate I would use crushed coral in the filter (bagged, just like carbon). True marine sands can alter the pH but then you run in to the same issues as many non-aquarium sands (wrong grain size, grain size isn’t uniform, etc.). Coarser marine substrates like crushed coral will just trap a lot of debris, just like gravel, so it is still more maintenance than necessary.For aquariums that incorporate live plants, it is important to have two layers of substrate present. The bottom layer, which is the one which anchors the plants and to which their hair-like root system derives nutrients, should be labeled for that purpose. Commonly, these sorts of substrate contain nutrients needed to foment proper plant growth. The second, topmost layer should be composed of either gravel or freshwater aquarium sand. This will help keep the nutrient-rich elements of the lower substrate needed by the plants from diffusing into the water.