Introduction: Modular Hydroponics - Low Profile Reservoir

The latest and first addition to the Modular, Windowsill, Air Powered, Hydroponics Herb Garden/Experimenter is a low profile reservoir. It was going to be four feet long, but mistakes and practicality dictated otherwise. This is an improvement over the 2L bottle for many reasons, with volume being the main driving force and the rest as very pleasant side effects.

By laying the reservoir on its' side, we effectively increase the surface area that the air is pushing on. This allows the little air pump to move greater quantities of water over greater distances and heights, with little or no added strain. We also change from a 2L bottle to a drain pipe, allowing flexibility in size/volume.

Drain pipe was my obvious choice for cheap and readily available material, soooo I actually went and purchased a piece of pipe, the end caps, and the cement. I proceeded to cut and drill and glue it together. When I awoke after succumbing to the fumes of the cement, I came to two quick realizations. This stuff is EVIL and it's a good thing that I will not be having any more children. After it failed a pressure test, I also realized that I suck at using this stuff and/or am too impatient to let it cure for 48 hours. Probably both. Anyway, yet another reason to reinvent the wheel and nurture my masochistic tendencies. And to satisfy your apparent need for self abuse, please read on........

Step 1: Conclusions and Considerations

Due to the mistakes that I have made, and some that I haven't, I have come to the following...


1. The air inlet and vent MUST be as high as possible and DEFINITELY above the water line.
2. The nutrient siphon MUST be as low as possible.
3. It helps a LOT if you can see inside and therefore, know, what's going on inside the reservoir. Enter the 2L pop bottle.
4. I can do it better (suited to my needs), faster, stronger (sort of.... in some ways.... maybe... kinda), definitely cheaper AND easier on my lungs and immediate environment than if I used conventional methods... I think.
5. Most importantly, if you don't like the results, you can do it over for free.


1. Modifications/alterations/experimentin' must be made from "free", easily replaceable parts aka recyclables. Purchased goods are to be treated as irreplaceable... as much as possible/practical.
2. Modules must be easily replaced around the "HUB" of the system for CONVENIENT maintenance. I LIKE SWAPPABLE SPARES.
Note - The "HUB" is only a TEE connector. It's a secret, don't tell anyone. It's the only "central" point I can see.
3. Must be simple in operation and construction and therefore, hopefully reliable and undaunting.
4. Most importantly, if you don't like the results, you can do it over for free.

Step 2: What You Need

After several failed attempts, I needed psychiatric help..... probably needed it anyway, so..... You will hopefully not. I did not include photos here as it is largely reverse engineered from "something" I was satisfied enough with, at one point, to make an instructable and a run-on sentence from. I tried to include as much as possible in the steps photos.

1 length of 4 inch drainage pipe. Doesn't matter how long, so use your space as desired.
2 ea 2L pop bottles, of a diameter great enough to EASILY slip over pipe. (not PEPSI .... bottle shape)
2 ea pop bottle caps (they can be PEPSI)(You could use 2 more to actually use as caps during transport)
Hot melt glue
Non-toxic crayon
1 ea small, self tapping screw
Approx 1 ft length of 1/2 inch Vinyl tubing
Short length of 1/4 inch aquarium air tubing
1 ea 1/2 inch rubber grommet

Tools and drill bits as required, including a heat gun or similar source of heat.

Step 3: Pipe Prep

1. Cut the pipe to the desired length with smooth, even ends.
2. Bevel the edge to 45-ish degrees.
3. Smooth away any burrs or nicks. It is important that the edges to be smoooooth for the best seal.
4. Apply a generous amount of hot melt to beveled edge, being careful not to increase the outer diameter of the pipe end. Will melt and create a seal.
5. Apply a very generous amount of wax, in the form of your favourite colour of non-toxic crayon, in a continuous line around pipe, near end. Will also melt and create a secondary seal, at least in my mind. Don't know if it's necessary, buuuuuut.........
6. Cut a bottle in half and slip the top half over the prepped pipe end, so that the cut edge is about an inch past the crayon line as shown.
7. Repeat steps 1 thru 6 at the other end of the pipe.

Step 4: Sealing and Shaping the Ends

This step is NOT safe and I do NOT recommend that you be as silly as I, unless in an EXTREMELY WELL VENTILATED AREA.

This step WILL require practice and you WILL get better with patience and observing the process. When heated, pop bottle plastic will first become pliable, then it will shrink some, then it will crystallize and change colour as the temperature rises. We want to avoid the crystallization caused by over heating, so heat slowly and gently for best results. The use of a heat shield and/or deflector may help achieved desired results.

In this step, we will be using the bottle as shrink tube, to first form an air tight seal and then shape the ends so that they face upwards (there isn't an upwards until be make one) with the lip of the cap extending beyond the pipes diameter. One end will be for the air access and the other for nutrient feed tube access.

Position the bottle top, so that there is enough plastic extended to form the end. This stuff shrinks, not stretches. I keep changing my attack a little each time, so I just go by eye.

1. Using a heat gun, gently heat the portion of the bottle covering the pipe, causing it to form a tight seal to prevent slippage during the bending process. Do not heat the dome yet, so keep heat directed so that it only affects the desired area. You could use a foil shield or deflector if you wish.

2. Secure the unit down to prevent movement during the next steps. Do the next steps in a well ventilated area, keep heating to a minimum and DO NOT overheat as the plastics WILL off gas toxic fumes.

3. Insert a long shaft into the tube, through the bottle neck,as far as possible. This will be used to get the desired shape while applying heat. While gently applying heat to the bottom side, press down firmly on the shaft, bringing the neck of the bottle to the edge of the pipe and keeping as open a channel as possible between the edge of the pipe and the neck of the bottle. Heat the top side as required to achieve the desired shape. Once generally shaped, secure into final shape, gently reheat the entire bottle top until pliable to release any strain and allow to cool.

Step 5: Caps

One cap for each end of the tube.

The pictures should be self explanatory in this step.

Step 6: Assembly

1. Screw on air cap.
2. Screw on liquid cap, ensuring that tube reaches and presses against bottom of pipe reservoir.
3. Insert into the Modular, Windowsill, Air Powered, Hydroponics Herb Garden/Experimenter where the 2L bottle reservoir currently is, as shown.
4. Empty current reservoir contents into the Pipe Res.
5. Test and make adjustments as required/desired.

Sequence through the pictures to see the ease in which parts are swapped in and out.