Hi everyone, my name is Roger and I love this website. Long-time reader but first-time contributer, so please leave plenty of questions, comments, and feedback at the end :)
I recently started keeping freshwater fish in an aquarium which came with an Aquaclear 30 Hang-on-Back (HOB) power filter. While the filter works fine, I noticed that a lot of the clean water that flowed out went straight back into the intake tube to the left (I keep the set the flow to low since I have slow-moving fish.) So basically, the HOB would continually refilter the same small amount of water while leaving the rest of the tank water uncirculated and dirty.
In my mind, there were two possible approaches to this problem. I could shift the filter to the right of the tank and extend the intake tube horizontally to the left with some PVC joints and tubing. Or, I could move the filter to the left and make something to divert the clean water flow to the right, away from the intake tube. Fortunately, the decision was made for me: moving it to the right would've covered some light switches, so... "to the left, to the left!"
This project is quite simple and offensively inexpensive. By the end you should have an efficient, barely noticeable trough that funnels the water away from the intake tube, thereby circulating the aquarium water. Your fish will love you for it!
Here's some photos of a prototype I made. You probably already have a sense of where this project is going just by looking at it:
Step 1: Things You Will Need
1. HOB filter that works
2. Tape measurer
3. Sharpie Pen
4. Hobby knife
5. Shears or strong scissors (depending on how thick your cup material is.)
6. Smaller scissors for more precise cuts
7. A good pair of eyeballs (preferably your own) for eyeballin' measurements
8. Plastic cup (several for trial-and-error)
There is a mindboggling variety of plastic cups in the world, so which one is right for this project? It's really your call.
In general, what you're looking for is a relatively inconspicious cup so it won't detract from the look of the tank (unless you want a 7-Eleven Big Gulp monstrosity to be the focal point of your aquarium!) Clear plastic is preferred since it's durable and see-through. As for size and thickness, it depends on your filter. Mine is just a wimpy Aquaclear 30 (the second weakest of all Aquaclear HOBs), so I did not have to worry too much about the water flow overpowering and bending the cup as it diverts water. If your filter has a greater output, then you should look for a sturdier cup.
The cup material should not be brittle since we'll be bending and contorting it to stay in place under the HOB. It should also be tall enough to catch the whole "waterfall" of clean water from the filter (mine was 3 1/4 inches.) It would also be helpful if the cup has a reinforced lip to bear the weight of the water. Oh, and remember to clean the cup thoroughly so you don't infect your fish with cooties or alcohol poisoning :)
I know, all this fuss over a stupid cup. Don't worry, it'll all become clearer as the project progresses. I just happened to find a stack cheap ones under the sink. They're kind of like the ones your dentist gives you to gargle with after invading your mouth. Perfect.