This technical update set out to determine the most suitable diffuser plate material for the biosand filter (BSF). Materials tested include plastic cardboard, acrylic plastic, and galvanized steel.
Moving forward, it is recommended to use plastic carboard as the diffuser material, since it is the cheapest and easiest to construct.
The plastic cardboard plate is the easiest to construct, assuming an electic drill is readily available.
All diffuser plate materials yielded effective protection of the sand layer, since in all cases the sand layer was not significantly disturbed while pouring water into the filter.
Reducing the number of holes (50 vs. 100) did not appear to have a significant impact on the performance of the diffuser (in terms of protecting the sand layer).