Proper Substrate for the Turtle Tank

A few questions we get asked frequently here at Turtle-Tech, from our beginners in the turtle hobby, are in regard to the bottom substrate in their turtles aquarium: “What’s the best substrate to use at the bottom of my turtles tank” or even: “Should I have substrate at all, or leave the bottom of my turtles aquarium bare”?

A proper layer of substrate at the bottom of any aquatic aquarium environment, whether it be for turtles or tropical fish, actually performs a few different purposes. All of them useful in maintaining a safe, stable situation for the animals living within the aquarium. First of all, the substrate (most commonly a layer of clean gravel) obviously goes a long way in creating a natural looking environment, which in turn allows the turtles to be comfortable in a home that naturally feels safe and “normal”. But besides the aesthetic value of the substrate, this layer of gravel, preferably an inch or so thick of a medium size pebble, provides an excellent area for colonization by beneficial nitrifying bacteria. These bacteria that live among the gravel brake down the turtles waste products and help allow the water to remain clear and clean. Without a healthy population of these bacteria, the turtles aquarium can remain cloudy, smelly, and generally unhealthy for the turtles living in the water. Most quality filtration units provide some biological filtration capacity, but a biological gravel bed goes a long way in assisting the filter and the stability of the aquarium.

So how much gravel should I use? The most effective gravel bed for turtles is a one inch layer of natural pea gravel of a medium grade (approximately ¼ inch size), this size pebble allows water to pass freely around it, providing oxygenated water to the bacteria. A gravel smaller then this will restrict the water flow, as will a bed deeper than one inch. Caution should be used when using fine sand, as it allows minimal water flow and can create “dead areas” of no oxygen in the aquarium where non-beneficial bacteria can develop. If fine sand is used it should be turned frequently to eliminate these dead spots.

But doesn’t the gravel at the bottom get dirty? Sure, your gravel bed requires a little maintenance as does everything in the aquarium. Each month when you preform your 25% water change, siphon out the water using an aquarium gravel vacuum. Simply move the vacuum throughout the gravel bed to remove any unwanted buildup. If you take care to keep your gravel substrate clean, the bacteria within it will reward you with clear water and a healthy environment for your turtles.

But can’t my turtles eat the gravel? In nature: lakes, ponds, rivers and creeks, turtles come in contact with multiple forms of environmental substrate every single day, throughout their entire lives. Can turtles at time ingest some trace amounts of substrate while feeding and foraging in nature? It appears possible, as wild caught turtles have been known to pass small amounts of substrate after capture. Does it appear to be a problem? Obviously not in nature. Could it be an issue in a captive aquarium situation? Anything is possible in rare isolated cases (such as a turtle mistaking green or red colored aquarium gravel as a food source), but it is extremely unlikely as reports of problems relating to over ingestion or impaction of substrate are very rare.

Always make sure to completely rinse the substrate to remove any silt or debris before adding it into the aquarium. Again, colored aquarium gravel should be avoided in the odd chance the turtle might misjudge it as a food source. Place an even layer about one inch thick throughout the bottom of the aquarium and be sure to vacuum the substrate during your monthly water changes.

For more information on the general care and husbandry of Aquatic Turtles, please check out more great articles on the: