Constructing the Stacked Sieves

We recommend that you construct a stacked filter set (Figures 11, 12) for each species of copepods you intend to culture. For a 300 L tank, we elected to use a 6” diameter PVC coupling for the lower sieve, and a section of 6” PVC pipe for the upper sieve.

 

 

 

Figure 11. Stacked filter set.

Figure 12. Stacked sieve schematic.

Upper Sieve: For Adult Capture

• Cut a 9” section of 6” diameter PVC pipe. Cut squarely across the pipe on each end. Sand the edges smooth and flat.
• Apply a thin coat of silicone aquarium sealant to the lower edge of the pipe section.
• Stretch a piece of 150 µm Nitex screen carefully over the mouth of the 6” pipe.
• Apply a 0.5 cm ring of silicone aquarium sealant to the screen immediately above the pipe. Avoid smearing silicone over the free surface of the Nitex.
• Work the silicone into the screen (over the PVC pipe only).
• Sand the pipe exterior such that it fits closely into the coupling used as the lower sieve. It must be capable of being removed without loss of copepods or eggs from either sieve.

Lower Sieve: For Egg and Nauplii Capture

• Use a Dremel tool, jig saw, or hack saw to cut three triangles from the bottom edge of a 6” PVC coupling. This allows drainage while sieves are submersed.
• Cut a ½” section of 6” diameter PVC pipe. Cut squarely across the pipe. Sand the edges smooth and flat.
• Stretch a piece of 53 µm Nitex screen carefully over the ½” ring of 6” pipe.
• Work the ring into the base of the coupling, capturing the Nitex screen smoothly.
• Slide this in almost to the ridge in the center of the coupling; apply a 0.5 cm ring of silicone aquarium sealant immediately below the ridge, but above the screen.
• Work the ring & screen up onto the silicone.
• Smooth the bead generated into the screen over the ring. Avoid smearing silicon over the free surface of the Nitex.
• Place a small bead of silicone under the lower edge of the ring.

Use of the Stacked Sieves

• Nest the sieves.
• Immerse the stacked sieves in treated seawater; remove the air bubbles under the sieves.
• Screens must remain submerged and wetted during the entire process. We use an oil collector from an automotive store (Figure 13).
• Connect the siphon hose to the siphon head, initiate the siphon, insert into the hose into the stacked sieves. Clamp hose to the stacked sieves.
• Clogging of the sieves may occur during collection and could result in the loss of adults and eggs. Be vigilant. Shake the sieves gently to improve flow during collection.
• Rinse upper sieve (150 µm) over the lower sieve (53 µm) before collecting the adults and detritus in the upper sieve.
• Collect contents of upper sieve into a 2 L beaker.
• Collect contents of lower sieve into a separate 2 L beaker.

Figure 13. Stacked sieve in collecting pan.

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