The pore size to use will depend on the organism you want to detect and the level of suspended particulate in the water you are sampling.

0.45 µm = Microbial studies such as fish pathogen detection or microbiome analysis.

1.2 – 5.0 µm = Fish, macroinvertebrates, bivalves, etc. (Metazoan studies).

We generally recommend 5 µm filters because they work well in a wide range of sampling habitats. 5.0 µm filters will actually capture slightly less eDNA per liter of water collected than 1.2 µm filters, but 5.0 µm usually allows for a much larger water volume to be filtered prior to clogging. The net effect is that 5.0µm filters will capture more total eDNA if the water volume is maximized.

Yes. We designed the Smith-Root eDNA filter housing to be compatible with a wide range of filter membrane materials. Please contact us if you do not see the pore size or material you want to use. Minimum orders may apply.

A wide range of sample water volumes have been used in the eDNA literature. Generally speaking, the goal is to maximize water volume per sample to increase species detection sensitivity, and also to standardize the water collected per filter sample within a study. However, the amount of water that can be collected at given pore size varies substantially between different habitats. A pilot study can be done to determine the realistic sample volume for your study system (please see the eDNA Sampler manual for details).

Filter samples of 1L – 5L are common water volumes for the eDNA Sampler system. We also recommend a minimum of 0.5 L per sample for the Smith-Root eDNA Sampler. If you cannot achieve 0.5 L per filter sample, we recommend increasing the eDNA Sampler pressure threshold or increasing the filter pore size.

New tools are currently in development to help with eDNA study design. The required number of samples will depend on the desired species detection probability, eDNA assay sensitivity, environmental factors, and other technical details. If you are interested in using the Smith-Root eDNA lab services, we can offer you guidance on study design in collaboration with our partner laboratory Precision Biomonitoring.

Online resources are also available for estimating your species detection probability under different sampling designs and assay variables. https://edna-probability-of-detection-calculator.shinyapps.io/eDNA_PrDetection_2/

For new studies we recommend a flow rate of 1.0 L/min as a starting point. When the water has a very high particulate load, a lower flow rate is recommended (e.g. 0.5 L/min) to help maximize the volume filtered prior to clogging. Higher flow rates (e.g 1.4 L/min) can be advisable when using multiple filters in the system (triplicate sampling) because the flow rate at each filter equals the displayed value divided by the total number of filters.