How to Make an Algae Test Photo Bioreactor...Part Four




Introduction: How to Make an Algae Test Photo Bioreactor...Part Four

Cap Assembly

This multipart instructable gives a step-by-step instructions on making an algae test photo bioreactor. This can be used in any application that calls for testing and/or growing algae, to determine maximum growth rates, best nutrients, etc., such as...

Making algae biodiesel,
Animal feed,
Organic fertilizer,
Health food supplements and many more.

Because this is more involved than can be explained clearly in a single instructable, I'll have to include multiple parts.

You can also download a complete free eBook here:

It includes a complete parts list, color diagrams, step-by-step instructions, and full color photos.

Step 1: Cap Assembly...1


(10) 1.25 PVC threaded plugs
(10) Bulk Air stones
(20) 1/8 x � Barb Adapter
(1) Aquarium Silicone air hose
(10) �w Adaptors
(1) Tube 3M 5200 Marine Adhesive
(10) Check Valves
(10) 1.25 PVC Slip and Thread adapters

Tools Needed:

Drill press or power drill.
1/2" drill bit
9/16" deep socket
Socket wrench
Utility knife
3M 5200 Marine adhesive

Assemble all the parts and tools necessary before beginning:

Step 2: Cap Assembly...2

Start by drilling a �e in the center of the PVC end plug.

A drill press works best of this as you can make extremely exact holes.

A regular hand drill will also work. Keep in mind if youre using a hand drill the caps will have a tendency to spin away from the drill. Youll need some sort of clamp or vice to keep the plug and drill bit steady.

Working in plastic and PVC, using a wood drill bit at medium speed and steady pressure seem to work best.

Step 3: Cap Assembly...3

Drill 10 caps.

Step 4: Cap Assembly...4

Carefully apply a small bead of the 3M adhesive directly under the barb nut.

Step 5: Cap Assembly...5

From inside the PVC cap, thread the barb into the PVC cap turning the hose barb adapter clock-wise.

Step 6: Cap Assembly...6

Seat the hose barb firmly into place using a 9/16" deep socket and extender. Carefully tighten, but DO NOT over-tighten.

The hose barb should have approx. 3/8 of an inch extending from the bottom of the PVC cap. Put a small bead of adhesive around the threads.

Step 7: Cap Assembly...7

Thread the right angel elbow unto the barb thread. Use your socket and extender to tighten as needed.

Step 8: Cap Assembly...8

Apply a bead of adhesive around the BOTTOM half of the hose adaptor.

Step 9: Cap Assembly...9

Carefully thread the barb onto the right angle. You may need to use a pair of pliers or the socket to seat the hose barb firmly. DO NOT over tighten.

Step 10: Cap Assembly...10

Cut a piece of tubing about 1.25 and connect to the air stone.

Step 11: Cap Assembly...11

Press the air tube with the air stone connected to it over the barb located inside the PVC cap.


If pressing the air tube becomes difficult or kinks, place the end of the air tube into hot water for about a minute. This will soften the air tube and make it more malleable.

Step 12: Cap Assembly...12

Your cap assembly should now look like this:

Step 13: Cap Assembly...13

Now do 9 more cap unit assemblies.

Cut 10- 1 inch pieces of tubing.

Step 14: Cap Assembly...14

Connect the one inch tubing to the barb extending from the cap.

Step 15: Cap Assembly...15

Spread a bead of adhesive on the threaded coupler.

Step 16: Cap Assembly...16

Screw the plug into the coupler.

Step 17: Cap Assembly...17

Connect a check valve to the other end of the tubing making sure the arrow points TOWARD from the cap assembly.

Step 18: Cap Assembly...18

Now cut a piece of tubing approx. 4 foot long, and connect the tubing to the other end of the check valve. The completed check valve assembly should look like this, except arrow should point TOWARD cap:

TIP: Try blowing into the tube. You should be able to blow air all the way through. If obstruction, turn check valve around.

Step 19: Cap Assembly...19

Now complete a check valve assembly for each of the other 9 cap assemblies. Put them all in a box and set them aside for later use.

Your cap assembly and one of the most difficult parts of your PBR construction is now complete.

Step 20:

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    2 Discussions


    10 years ago on Step 1

    no, they aren't. the hose barb is 1/8th. and the male fitting is 1/4". the elbow is also 1/4" Can send you the pictures of the packages if you like.


    10 years ago on Step 1

    Those are not 1/8 parts. Looks a lot like 3/8 or 1/2 to me.