Part 3 of 4
Now you need to make the "waterfall pipe". It's exactly like what is used on those tabletop decorative waterfountains. I used a 1" ID pvc pipe (1-1/4 OD), from any hardware store. Before you cut it, install a cap (I used 1") on one end, using teflon tape to seal it:
Aquatic Eco-Systems: Cap, Slip 
You need to water-test the cap too, so fill the pipe up with water (cap at bottom) and check for leaks. If no leaks, empty water and dry off. Now set the pipe down on the top of the bucket and position it so that the cap touches the bucket:
Measure 1.5" from the outside of the bucket, mark the pipe, and cut it there:
Now get another hose adapter that matches your vinyl tubing size:
Aquatic Eco-Systems: Female Adapters
Find a "reducer" that takes the size of the pipe down to the size of this hose adapter; I used a 1" to 3/4":
Aquatic Eco-Systems: Reducing Male Adapters (MNPT x Slip)
Attach the reducer to the other end of the pipe using teflon tape:
And screw the hose adapter onto the reducer, using Teflon tape:
Screen: The screen pictured here is a plastic tank divider (get the biggest one, and cut it down), but almost any stiff and porous material will do, as long as it stands up straight:
Aquatic Eco-Systems: Tank Dividers
Even if you don't use a tank-divider, get one anyway so you can use the plastic edges that come with it to hold your screen in place. Window screen (non-metal only) can work, but would not stand up by itself too well, so you'd still need to build a non-metal frame to hold it. What also works good is knitting backing material. Whatever screen material you use, get enough to make THREE full screens, because you are probably going to mess up at least one the first time.
Size the screen so it fits in your bucket, using the dimensions you get from measuring the bucket; make the screen a little bigger than you think you need so you can trim it to fit:
Cut the screen to shape, and attatch the edges (that come with the tank-divider); your screen should now have a "V" shape, and about a half inch of the screen should stick out past the edges on the top:
Now lay the bucket down sideways, and lay the screen on the bucket so that the extra half-inch of screen sticks out past the top of the bucket, and the edges are even with the top:
Now mark the bottom of the edges about 1/4" up from the bottom of the bucket. And mark the bottom of the screen about 1" from the bottom:
Cut the screen bottom, and edge bottoms, and clip on the small edging that comes with the tank-divider:
Cut 1/2" off the top corners of the screen, and use sandpaper to make the screen rough on both sides (turf will stick to it better).
Next is the waterfall pipe "slot" that the screen goes in. Start by measuring how wide the top of the screen is, then mark that length plus 1/4" more on both side so the screen can fit in easily. Then mark the slot to be 1/8" wide:
Don't mark the slot too wide; just start with 1/8", and you can increase it later if you need to, based on the flow you get. Now comes the only difficult part of the whole project, cutting the slot in the pipe. You may need to get help to make the cut; anyone who builds models, or does woodworking, should be able to help. I used a Dremel moto-tool with a "cut off wheel":
It might be a good idea to make TWO pipes in case you or your helper mess up the cut on one of them. Now install the pipe onto the screen/bucket by tilting the pipe and starting at one side, then lowering the pipe over the rest. You may have to wiggle the screen in some places to get it to fit in:
Now figure some way to hold the hold the pipe to the top of the bucket. I used office clips on both sides of the pipe, with a paperclip across them, but you can use anything that works for you (string, tape, clamps, etc.) You will be taking the pipe on and off several times as you make adjustments, so don't attach it permanently.
Now time to test! Connect up the pump to the pipe with vinyl tubing, and use sink or tub filled with tap water:
Run the pump and make sure the water covers most of the screen. Here's a video of the first time running water through this one:
http://www.radio-media.com/fish/FlowTest.mpg YouTube - Turf Algae Filter in a bucket, Flow Test
Adjust your pump output and screen placement in the pipe so that water flows out smoothly without spraying (the water should only flow down the screen; it should not shoot out sideways.) If water sprays sideways (hitting the side of the bucket), then the slot is too narrow, or the flow is too much. First try reducing flow with a ball valve, a smaller pump, or a clamp on the hose. If you can't do these, then widen the slot with a Dremel or file.
If, on the other hand, all the water flows out of the first part of the pipe and does not make it to the end of the pipe, then the slot is too wide or the flow is too little. You can fix this by adding more pump flow, or by adding extra layers of screen (making the screen thicker) at the part where it goes into the pipe. Last resort is to just make another pipe with a slot that is more narrow. If you just can't get total screen coverage with water, it's ok since those areas will be filled in once the algae grows in other places.
If all looks well, then clip on the lights: My example bucket uses two 23 Watt, 5100K compact fluorescents "full-spectrum" (125W output equivalent):
23 Watt R40 Compact Fluorescent Flood 5100K Full Spectrum CFL