# Strange DIY filter idea



## winsonli (Feb 18, 2007)

Well this might be a stupid idea, but if it works I think I'll be a good filter for my nano tank.









*'pump' is actually a powerhead

The outer tubing is a filter hose of diameter, say, 1.6cm. It would be a compartment for the filtration media (activated carbon). Water would be driven in by a mini powerhead through an air tubing.

It'll work like a siphon. when the water from the powerhead passes beyond the u-tube, a continuous stream of water should flow. When water is continuously pumped in, it'll go down the narrow tube, reach the bottom of the thicker tube, flow upwards through the filtration media to the u-tube and return to the tank.

I'll add a sponge filter in the water intake of the powerhead to prevent any large particles from getting into the tubing. I guess the only load on the powerhead is the journey of water passing through the u-tubes, so the flow rate should be acceptable. Please correct me if I'm wrong.

I do not have room for cansister filters and do not want to use hang on ones. With this setup, I would be able to hide all the tubings behind the cabinet. If the tubings are long enough, I should have several liters of filtration compartment.

I know the water flow in the tank would be weak. Filter maintenance would be difficult as well. But apart from these would the idea work? 
And could the tubings be very long provided that they're below the tank?


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## schaadrak (Aug 18, 2006)

Looks like it would be perfect for small tanks. Pretty cheap and easy to make as well.

I wouldn't go below the bottom of the tank with it though, the head pressure might be too much for the smaller power heads. If your looking to increase volume, maybe put a few turns in it.

Also, you might want to make the lower portion easy to separate from the U-tube to help with maintenance.

Keep us posted on this project turns out.


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## freakmonkey1423 (Jan 21, 2007)

I really like this idea, I have a small pump that would work perfect for this. I would love to work with you to improve on the idea. I have been looking for a good diy filter for my nano and this is the best idea I have seen so far.


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## Freerider (Nov 8, 2006)

You could even make the tube extend down to the floor (or even bend it back up to the tank with some elbows), fill it with biomedia and you have one huge and cheap bio filter.


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## JERP (Feb 4, 2003)

You might consider using the power head to pull water out of the filter. That way if something goes wrong, the powerhead won't drain your tank onto the floor.


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## winsonli (Feb 18, 2007)

Thank you for your inputs.  

schaadrak,
Putting turns in the tube is a good idea. I'll include this into my design.

freakmonkey1423,
Glad you liked my design. Please share with us your finished product if you would try this design. I do not have the necessary parts to try it out yet. Thanks.

Freerider,
Do you have recommendations on biomedia? They should be small enough to fit into the pipe, while being not too tightly packed which would inhibit the water flow. I could only think of activated carbon.

JERP,
I think that would not be a concern. Nothing bad should happen if the power head fails. The water in the filter would not enter the tank and overflow it. On the other hand, Water would not be pulled from the tank as the siphon stops when both water levels are the same. Please correct me if I'm wrong.

I realized another advantage of this design. Aerobic bacteria would colonize in the earlier sections of the tube, and as they will use up the oxygen, anaerobic ones would colonize in the later sections. More anaerobic bacteria would be present compared to conventional filters.

I'm kinda busy right now and could not start this project yet. I don't have a power head yet as well. But I decided that filter tubings are too narrow. When I start the project, I'll be using PVC pipes instead. They're available in larger diameters. Per meter of 5cm diameter pipes would give around 1.9L of capacity (Note that the volume occupied by the air tubing is not taken into calculation.) A stronger power head could also be used.

I'll post pictures of the design when I have time to finish the project.


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## ed seeley (Dec 1, 2006)

Maybe you could make this even easier by incorporating a U-bend so the pipe bends back up towards the tank water level. This could then be fitted with a pipe connector to attach the pump feed to.

The bend could rest on the stand for more support.










The pump output can be plugged onto the top section that would keep it out of the pipework and allow you to get away with slightly larger filter media.
You could even add CO2 into the filter inlet and this will act as a great CO2 reactor too! I'm getting tempted to try it....


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## Freerider (Nov 8, 2006)

I would use PVC pipe (3 or 4") with Eheim Substat Pro as the Bio Media as it is small, round (good for water voids) and high in surface area. For the inlet i would use 1/2 or 3/4 inch pipe just snaked down to the bottom before the media goes in. I thought of this idea awhile back when i was looking for a cheap way to filter ponds. I ended up not using the idea because of head pressure (ponds being way below the top of the unit) but in your case it should work quite well.


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## JERP (Feb 4, 2003)

Just make sure the tube doesn't fall off you tank while the pump is running (any small children around?). The filter will pack rather quickly, but it's only for small tank anyway.

looks good.


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