Fluval Stratum is a popular aquarium substrate used by many fish tank owners. As with all substrates, it’s important to change the Fluval Stratum regularly in order to maintain a healthy and clean environment for your fish. The general recommendation is to replace the Fluval Stratum every three to six months depending on how heavily stocked your tank is. If you have a lot of active fish or plants growing in the tank then you may need to change out the substrate more often than that. When changing out your Fluval Stratum, make sure that you rinse it thoroughly before adding it back into the tank as this will help prevent any cloudiness from forming in the water column due to excess debris or particles suspended within it. Additionally, be sure not to add too much new substrate at once as this can cause an imbalance in pH levels which can be harmful for your aquatic life. By following these simple guidelines and replacing your Fluval Stratum every few months, you can ensure that your aquarium remains safe and healthy for all of its inhabitants!