Originally Posted by CottonDandyBubbleFun
I didn't mean live saltwater sand for my freshwater aquarium,
I was just wondering if I could have beneficial bacteria live in a
freshwater sand bed to assist in breaking down yucky stuff.
That occurs naturally in every aquarium (or should
). "Live sand" bought is the saltwater stuff, so I assumed you meant using that.
The substrate in a freshwater aquarium will naturally develop a host of different aerobic and anaerobic bacteria. These break down organics (fish waste, uneaten food, dead fish/plant matter, dead bacteria, etc) that will seep into the substrate. With live plants they contribute greatly to this process as plant roots release a lot of oxygen for the bacteria. CO2 is produced during this, along with heat obviously, and the latter draws the cooler water down and the warmer water up, circulating through the substrate. Malaysian livebearing snails are handy in this, as they creep through the substrate keeping it more "loose" and allowing better water movement.
Without live plants the end result of this natural process has to be controlled via water changes. Live plants, and the more there are the better, reduce this need but don't totally eliminate it [at least in my view].