Laboratory filtration troubleshooting: 10 common problems and solutions

1. Filter clogs before the sample finishes

Cause: particulate load exceeds the filter's capacity. Fix: add a coarser prefilter stage or switch to a multilayer/depth-media format. See our clogging prevention guide.

2. Flow rate is much slower than expected

Cause: pore rating too tight, insufficient filtration area, or inadequate vacuum/pressure. Fix: increase diameter/area before loosening pore rating, and confirm your vacuum or pressure source is adequate.

3. Sample volume comes out lower than expected (analyte loss)

Cause: membrane binding the analyte, or excessive dead volume relative to sample size. Fix: check for low-binding membrane options and use the smallest filter format appropriate to your volume.

4. Housing leaks or fails under pressure

Cause: chemical incompatibility degrading the housing, or exceeding its pressure rating. Fix: confirm housing material compatibility, not just membrane compatibility—see our housing materials guide.

5. Membrane won't wet

Cause: hydrophobic membrane (like standard PTFE) used with an aqueous sample. Fix: pre-wet with a compatible solvent, or switch to a hydrophilic-treated variant.

6. Unexpected peaks or noise in analytical results

Cause: membrane extractables contaminating the sample. Fix: switch to a low-extractable or HPLC-certified filter line—see our HPLC sample prep guide.

7. Microbiological recovery seems low

Cause: wrong pore size for the target organism, or contamination introduced during handling. Fix: confirm pore size against the organism and method, and review aseptic technique.

8. Filter doesn't seal to the funnel or housing

Cause: diameter mismatch. Fix: confirm the membrane diameter matches the hardware exactly—an undersized membrane can let sample bypass the filter entirely.

9. Inconsistent results between batches

Cause: lot-to-lot variation in an unvalidated or loosely specified consumable. Fix: standardize on a specific SKU and request lot documentation for critical applications.

10. Not sure which of these is actually happening

Fix: describe the symptom, your sample, and your current filter spec to us directly—diagnosing from a description is often faster than trial and error.