Use a Pen to Increase Bubbles in Your Fishtank!




About: Applied Physics Major.

If you have a fishtank, it is likely you might also own an aquarium pump for enhancement of motion and relaxation of your tank. Most aquarium pumps sold have two outputs so that two different decorations may be used in the tank at the same time. I only have one such decoration, a Chinese Dragon. I also keep my diving knife in my tank, just so the fish know who's boss!

My dragon pumps out about 3 bubbles a second, but I thought I could get more through some creative engineering. In this instructable, I will show how I doubled my bubble output with the use of a single pen, some glue, and my soldering iron.

Step 1: Materials

This is a simple project, and you'll need the following:

1 Pen (Bic or similar style)
Aquarium pump with 2 nozzles
Soldering iron
a short length of the hose from your pump hose

Step 2: Checking the Hose Fit

First, you need to take the pen apart. This is so you can check if the hose will fit the pen you selected.
You want to make sure that the hose fits snugly in the pen tube body before going on. If it doesn't you might have to glue the hose in or attach it another way. My hose fit snugly, which is important to keep pressure from escaping.

Step 3: Drilling for Oil (not Really)

Use the soldering iron to make a small hole for the cap of the pen to fit into. The idea here is you want the hole to be small enough to fit the pen cap into just barely.

Always solder in a safe environment, with a window open in this case because you will be creating fumes.


After you've created a small hole and the pen tip fits snugly, you should glue around the hole to help seal it. You don't want any air to escape!

Step 5: Connect the Tubes

Insert your hose cuttings into the ends of the pen.

If they fit snug, you're basically done.

Step 6: Connections....

Attach the two hoses to your aquarium pump, and connect the hose leading to your decoration to the pen cap.

Step 7: Results!

I noticed a massive increase in bubble production!
More motion in my ocean.

Check out the before and after shots.



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    14 Discussions


    7 years ago on Introduction

    Your step ware you glue around the hole to help seal it because you don't want any air to escape, I see you using Elmer's white glue. I think you should be using a more waterproof glue like aquarium silicone sealant because white glue won't hold up very long in water. Super glue would also work well for the small amount that you need. Nice idea though : )


    7 years ago on Introduction

    you DO know that they have a T-valve for this purpose right...? these things are dirt cheap, albeit you get the satisfaction of making your own.

    1 reply

    Reply 7 years ago on Introduction

    yea, the T junctions are usually 5cents at the pet shop. The idea being to use 2 air stones in the tank rather than 1 super powered one . This fights stale water collecting in one area of the tank i say. So , i opt for 2 weaker stones over 1stronger stone . Just me tho.
    Good reuse of on-hand materials Disturbed1035 , you didnt have to drive to the store for a tiny plastic bit =)


    7 years ago on Introduction

    Does the pump have a single motor, or do the two outputs have separate motors? Because if the outputs are common, then just blocking the other output should achieve the sane result.


    7 years ago on Introduction

    Any half decent pump will have two outputs, One for each phase of the mains frequency.
    IE. 50Hz mains with a single action pump, will produce 50 bubbles( I was going to get into maths, But Its going to be pointless).

    My point is, Most cheap pumps are single valve, Your lucky to have to have a dual valve pump. Though you never used it before (I figure). and wonderd how to use this extra(thing).

    The dual valve(thing) will give you 100 bubbles(Half is almost for free) :O

    Join them together and you get 100 bubbles(surprise) , Surface tension may blur whats really going on.

    Ill Try a poor way of explaining.
    A Single valve pump will push air on one part of the AC mains
    A Dual valve pump will push air on both (1/2) phase of the mains
    Join them together and you basically make a full wave rectifier for air.

    You may notice that a pulse of air comes from one then the other, Then the other to one.
    It would be hard to actually measure this, Though I can tell you
    If your mains is 60Hz your dual valve pump will push 120 of bubbles
    If your mains is 60Hz you single valve pump will push 60 bubbles

    What I mean to say is both of those outlets on your pump are not pushing air at the same time. If you only ever used one outlet on your dual pump since you started getting your tank, It no wonder you think your getting more for free. :O

    If both outputs are not being used they use still consuming power(Though not at much as just being open to the air).

    Its a good thing you worked out how to use the second outlet.
    Yes joining them will almost give you 2 times more air, With almost no extra power.


    1 reply

    Thanks for the input! I actually took my pump apart before working on it to fix part of it. The magnets on both pumps were stuck, so I had to take it apart to move the transformer before I even started this. To help make your comment more understandable to others, I've taken apart and photoed one of my other pumps. You can see the two mechanical pumps and transformer within the housing, and the two rubber plungers used to pump the air to the right.
    My newer pump was designed in almost exactly the same way, although it is nearly two decades newer.


    7 years ago on Step 7

    Great write up, one suggestion is to use super glue, silicone (100% pure silicone), or epoxy glue that is fully cured. These glues have all been shown to safe in water for an extended period of time with out leaching chemicals into the water. Other that a great write up and I hope to see more.

    1 reply

    Actually, I ended up using some super glue on the connection after I made the instructable. If I had had epoxy I would have used that. Nothing is going in the water in my setup though, the tube that comes from the middle joint goes to the dragon. I've got a few other projects in the mix, but I don't want to submit instructions as I do them, I'll wait until it is finished!


    7 years ago on Introduction

    I've never had an aquarium pump with multiple outlets before. But I see the need for something like this if you did own one.