ASTM D4133-82(2012)

4.1.1 Sample size is more accurately controlled than with the use of a conical tow net.

4.1.2 Discrete samples from any depth are easily obtained.

4.1.3 Multiple or replicate samples are easily obtained.

4.1.4 They are adaptable to shallow ecosystems.

4.1.5 They allow for a stable collecting efficiency.

4.2.1 They generally are bulky and frequently require an electrical source.

4.2.2 They generally are costly.

4.2.3 They collect only qualitative samples, or semiquantitative samples when used with a volume register.

4.3.1 Pumps can induce mortality of the organisms and damage the delicate forms.

4.3.2 If tubing is not properly cleaned after use, contamination of subsequent samples can ensue.