How do you prevent sand from leaking into your fish tanks?

This topic is covered in Chapter 14 of the iAVs Handbook.

1- The ideal sand for iAVs should be medium-coarse, similar in consistency to table salt or granulated sugar, with virtually no fine particles below 200 microns in diameter. This allows for good drainage while preventing small particles from escaping.

2- Install a physical barrier at the drain points, a small piece of shadecloth, for example, is suitable. A handful of pea gravel may also be used.

A key design element of the iAVs is the strategic placement of the slit drain at the bottom of the side wall of the biofilter, facing the fish tank, rather than on the bottom. This positioning is crucial for system functionality and preventing sand leakage into the fish tank due to:

• Lateral Water Movement: This design promotes horizontal water flow, minimizing downward pressure on the sand bed, which reduces the risk of sand being pushed out through the drain.
• Gravity-Driven Drainage: Operating solely on gravity, the biofilter’s gentle slope ensures water flows toward the drain in a thin sheet, further reducing force on the sand and preventing dislodgment into the fish tank.