I found two 5 gallon plastic water jugs in the trash some time back. Now I could have simply returned them for the deposit at the store, but that wouldn't have been fun or original. Instead, seeking to furnish my home (a bit of a man cave, occupied by my teenaged son & me) and bring a bit of the outdoors inside, I turned these jugs into something completely different and unique.

This project uses the "body" of the water jug as an aquarium, while using the neck of the water jug to mount a lamp. Inside the aquarium is an undergravel filter using a silicone baking pan as the filter base and PVC pipe as the riser tube. The PVC tube continues above the aquarium section of the water jug and conceals the wiring for the lamp, which is mounted to a large PVC pipe bushing that fills the neck of the water jug. The lamp makes use of conventional lamp socket and wiring.

The following is list of things you need for one aquarium/lamp:

5 gallon water jug
1 1/4" slip in-glue on X 1/2" threaded female PVC bushing
9" round silicone flat bottom baking (cake) pan
Approximately 15" of 3/4" PVC water pipe
1" X 1" X 3/4" PVC tee fitting
3/4" X 3/4" X 3/4" X 3/4" PVC cross fitting
3/4" X 3/4" X 3/4" PVC tee fitting
3/4" to 1/2" PVC reducer fitting
1/2" threaded male to 1/8" threaded female reducer bushing - either galvanized or brass
1/8" close (short) threaded nipple - brass
lamp socket with switch
lamp cord
lamp shade harp
lamp shade
3 or 4 6" plastic cable ties
airline tubing (standard aquarium type)
small airstone (standard aquarium type for undergravel filters, sized to fit into 3/4" PVC pipe)
aquarium air pump

List of tools needed:

Dremel tool with rotary file or sanding drum
hole saw set - 4" hole saw, 1" hole saw (DON'T make a major investment in a hole saw set - I purchased mine on eBay for less than $12)
3/16" or 1/8" drill bit
electric drill
some tool to cut PVC pipe - either a ratcheting pipe shears or a hacksaw

Step 1: Modify the Water Jug

Prepare your water jug by using the 4" hole saw and electric drill: bore a hole immediately below the neck of the jug and above the "body" of the jug. This hole will provide access to the inside of the water, so you want it as high on the jug below the neck of the jug as possible. IMPORTANT: avoid drilling through the jug "seam" so to avoid weakening the water jug.

Now the slow and tedious part of this project: prepare the 1 1/4" PVC bushing to "plug" the neck of the bottle (and eventually mount the lamp) by fitting the bushing to fit inside the neck of the water jug. Using your Dremel (or other rotary) tool and sanding drums, sand/grind away on the outside of the 1 1/4" bushing until the bushing fits snugly inside the neck of the jug. You don't want to make the bushing so tight that you have to force it: you don't want to accidentally split the neck of your jug, but you want a good snug fit. Take your time - taper the end of the bushing, until you can push it by hand into the neck of the water jug.

BEFORE finally inserting the bushing, thread the 1/2" threaded male to 1/8" threaded female reducer bushing into the threaded hole of the 1 1/4" PVC bushing; then thread the lamp harp base onto the bottom of the 1/8" close (short) threaded nipple; then thread the nipple into the reducer bushing. This will provide the "mount" for the lamp socket when this project is finished.

Step 2: Modify the Silicone Baking Pan

Now prepare the filter base using the silicone baking pan. Using the 1" hole saw and electric drill, drill a 1" hole in the botton center of the baking pan. Then using the 1/8" or 3/16" drill bit and electric drill, drill lots (LOTS) of little holes all over the rest of the bottom of the baking pan (leave some intact pan bottom around the 1" hole to maintain the strength of the baking pan). Eventually water will flow through these holes, so lots of holes are important.

Step 3: Building the Undergravel Filter Mechanism

Next build the riser tube. This tube will also conceal the lamp wiring above the water line inside the water jug. You may have to do a bit of fitting in order that this tube fits well inside your particular jug.

Measure by sight your piece of 3/4" PVC pipe that will form the riser tube as follows: using the 4" hole you drilled into your water jug, hold the 1" X 1" X 3/4" PVC tee fitting against the inside bottom of the jug and insert the 3/4" pipe through the neck of the jug and down into the 3/4" fitting of the tee fitting, and attempt to estimate approximately how much pipe you will need to reach the 3/4" X 3/4" X 3/4" X 3/4" PVC cross fitting which will sit on the other end of this pipe. When correctly fitted, the two "sides" of the tee will be at the waterline of your aquarium, and of course, must be below the level of the 4" hole in your water jug. You will also be attaching the 3/4" X 3/4" X 3/4" PVC tee fitting and the 3/4" to 1/2" PVC reducer fitting above this tee fitting, and all these pieces must fit below the 1 1/4" PVC bushing that will be inserted into the neck of the jug.

If your water jug is similar to mine, the length of this pipe will be 9 1/4". However, you might want to cut this pipe long, and trim it to fit in conjunction with all the other parts.

Cut two additional 1 1/2" sections from the 3/4" PVC pipe to use as couplers for the other pipe fittings.

Now fit the filter together. SEE THE ATTACHED DIAGRAM IN THE PICTURES WITH THIS STEP TO SEE HOW THE PARTS FIT TOGETHER. Push the 3/4" fitting of the 1" X 1" X 3/4" PVC tee fitting through the 1" hole from the inside of the silicone baking pan, turn the dish over (bottom up) and "flex" the pan through the 4" hole in the water jug and down to the bottom of the water jug, so that the pan is upside down, the tee is upside down with the two 1" fitings inside the pan and the 3/4" fitting is up, facing the inside of the neck of the jug.

Now take the 3/4" to 1/2" PVC reducer fitting and attach it to one end of the "tee" of the 3/4" X 3/4" X 3/4" PVC tee fitting using one of the 1 1/2" sections of 3/4" PVC pipe, and use the other 1 1/2" section of PVC pipe and attach it to one end of the 3/4" X 3/4" X 3/4" X 3/4" PVC cross fitting. Insert the other end of the longer 3/4" PVC pipe into the end of the cross fitting across from the tee fitting, and wiggle and insert, using the 4" hole and the neck of the bottle, the pieces so that the 1" X 1" X 3/4" PVC tee fitting is on the bottom of the jar covered by the silicone baking pan, the longer section of 3/4" PVC pipe rises above it, topped in order (from bottom to top) by the 3/4" X 3/4" X 3/4" X 3/4" PVC cross fitting, the 3/4" X 3/4" X 3/4" PVC tee fitting, and finally the 3/4" to 1/2" PVC reducer fitting, which should be in the neck of the bottle and fit into the 1 1/4" PVC bushing when the bushing is inserted into the neck of the water jug.

You DO NOT need to glue these sections of pipe and fittings together - there will be minimal pressure differences inside and outside of the pipe, which will channel an air column that will power the undergravel filter.

Step 4: Build the Lamp

Now run the cut end (not the plug end) of the lamp cord through the 4" opening of the water jug and into the open end of the tee (not the cross) fitting of the riser tube, and then run the cut end of the lamp cord UP the tube through the 3/4" to 1/2" PVC reducer fitting, then through the end of the 1 1/4" PVC bushing in the neck of the bottle, and in turn through the1/2" threaded male to 1/8" threaded female reducer bushing and the 1/8" close (short) threaded nipple that were previously threaded into the threaded hole of the 1 1/4" PVC bushing in Step 2.

Wire the cut end of the lamp cord to the lamp socket using standard wiring techniques, then attach the lamp socket to the 1/8" close (short) threaded nipple. Attach the lamp shade harp to the lamp socket. DON'T worry about installing the lamp shade until the lamps are complete, and the aquarium is functional and stocked.

Step 5: Finish the Aquarium

PRIOR to this step, make sure that all the plastic pipe, fittings and silicone baking pan are installed in their final positions; that the lamp is wired and all electrical connections are tested; and that all parts fit together well.

Attach a small airstone to the end of a sufficient length of airline tubing and insert the airstone attached to the airline tubing through the same open end of the tee fitting that you also ran the lamp cord into the tube, and then direct the airstone DOWN through the 3/4" PVC riser tube to its bottom inside the modified baking pan.

You might want to attach the airline tubing and lamp cord to the water jug handle using the cable ties.

Now obtain and wash sufficient aquarium gravel or small marbles or small river pebbles that will be the filter media for the undergravel filter. Working slowly and carefully, spoon SMALL amounts at a time of the gravel/marbles/pebbles into the bottom of the water jug, taking care to completely cover the silicone baking pan to a level depth of at least 3/4"-1" with filter media. My water jug aquarium/lamp used approximately 4 pounds of aquarium gravel.

DO NOT TRY TO MOVE YOUR WATER JUG AQUARIUMS/LAMPS ONCE THEY ARE FILLED WITH WATER. Instead, move them at this point to their final positions, then fill the water jug with DISTILLED water to a level where at least half the open ends of the cross fitting are covered with water.

HINT: Using distilled water will reduce problems with water mineral deposits, which would be very hard to clean from inside of the water jugs.

Attach the open end of the airline tubing to a standard aquarium air pump and plug in. Air bubbles will emanate from the airstone inside the riser pipe and cause water to be drawn through the filter media at the bottom of the aquarium and the inverted silicone baking pan that suports it, rise in the riser pipe along with the bubbles and exit through either open side of the PVC cross fitting back into the aquarium.

HINT: Use a florescent or LED bulb at the top of the lamp to avoid heat build up from an incandescent bulb at the top of the aquarium.

HINT: Pick your fish or other aquarium creatures carefully. There is not a tremendous amount of water or space inside an aquarium of this nature.

As you can see (and perhaps reflecting my own eccentricities), I stocked each of my aquarium/lamps with a crayfish.

HINT: Spend some time reading about proper operation of undergravel filters. Undergravel filter media should NOT be washed, but allowed to accumulate waste from the water and develop a bacteria culture which breaks this waste down. Periodically siphon and replace some of the water, but never remove or clean the filter media in the aquarium. See, for general information, http://ezinearticles.com/?8-Reasons-Why-You-Should-Choose-an-Undergravel-Fish-Tank-Filter&id=4274935 , http://www.wetwebmedia.com/FWSubWebIndex/fwugfiltr.htm , and http://badmanstropicalfish.com/articles/article64.html .