Can you use normal rocks in a marine fish tank?

It is generally not advisable to use normal rocks in a marine fish tank. Here's why:

PH and Hardness: Many natural rocks may contain substances that can alter the pH and hardness of the water in your marine tank. This can create an unstable and stressful environment for the sensitive marine life. Maintaining a consistent and balanced pH level is crucial for the overall health and survival of your marine fish and corals.

Chemical Leaching: Some rocks, especially those containing high levels of certain minerals like calcium, iron, or copper, can leach chemicals and nutrients into the water. These chemicals can disrupt the delicate water chemistry balance in your marine tank, potentially harming your fish and corals.

Porosity and Shape: Natural rocks often have a rough and porous surface, which can provide hiding spots for unwanted organisms, including harmful bacteria and parasites. Additionally, the sharp edges and irregular shapes of normal rocks can pose a risk of injury to your marine life.

Decorative Purposes: While normal rocks may have a natural appearance, they may not create the most visually appealing or aesthetically pleasing environment in a marine tank. Marine aquarists typically use aquarium-safe rocks or decorations specifically designed for marine habitats to enhance the appearance of their tanks.

To ensure the safety and well-being of your marine life, it is recommended to use aquarium-grade rocks or substrates that are specifically designed for marine environments. These rocks are usually made from inert materials that are less likely to alter the water chemistry and do not pose potential hazards to your fish and corals. Some commonly used marine rocks include live rock, base rock, and ceramic rocks, among others. They have been treated and tested to ensure their suitability for marine aquarium setups.