Bubble Tubes...

[Timmyp]

Hi everyone,

I think this is the first time I've posted in Special FX, in fact it's the first time I've posted on the forums in absolutely ages.

I am looking at making some bubble tubes for use during a music performance, they'll also be used at home when they aren't in the theatre. Basically the effect I want involves a tube of acrylic (any other transparent plastics you can suggest?) a solar powered/mains powered (which would be better in your opinions?) air pump, and a ring of LEDs.

The air supply and LEDs would be in the casing at the bottom of the plastic tubing and the tube would contain water. The desired effect would be to have bubbles rising through the water while lit by the LEDs below.

The thing is, how can I make this work. It's a vague question I know, but surely I don't want the water entering the pump, and I can't see a way of stopping the water getting into the pump and air getting into the water creating the bubbles.

Have I got totally the wrong end of the stick? I know they're possible to make, but as a 15 year old student, with only my school workshops available is it possible?

Any help you can give would be invaluable to me, and also to my school!!!

Thank you for any help you can give, and I apologise if this is in the wrong section of the forum!

Timmy

[koncept]

just thinking quickly, you might be able to use some plexiglass and a ton of caulk to get your column. (im definaltely not the best to ask on that part) but i would then have a base at the bottom that it sits on and have your pump(s) and lights there. as for the pumps, im assuming a couple of fish tank pumps, in which case they have some backflow things that you can put in the line, that only allow air past and if water comes in it stops at that little peice. another option is to get the air hose to be higher than the top of the column.

[AVGuyAndy]

Sure it's possible. the acryllic tube will not be cheap tho. Then make some endcaps and connect some airlines, wire in some leds, and you're good to go. What you want is a check valve to prevent backflow. If you plan on using fish tank air pumps, they make check valves for this purpose, which will fit on fish tank air line.

[TheHeadhunter]

I know that fish tank shops sell air pumps with the hose ect for doing exactly this in fish tanks... so get one of those. The important thing is getting a watertight seal so the LEDs don't get wet. And I think mains supply (with a transformer) would be more reliable. What be really cool is if you use those LEDs that change colour and flash different colours!

[soundlight]

To change color get bipolar LED's and use a small circuit to swtich them. That would look very cool.

[koncept]

what next dmx control???

[jwl868]

I would also suggest looking around the internet for similar products and reverse-engineer them, so to speak. There is some trial and error in getting the air flow rate, maybe the pressure, the air tube orifice/nozzle diameter, and the bubble size for the right visual effect. If it’s a big tube, a fish tank bubbler pump may be too small.

A check valve in the air line (maybe even as part of the air pump) should keep water out of the pump. (Although it occurs to me, as I write this, that aquarium air pumps usually use a tube that is higher than the water level [going up and over the side of the tank], so the water cannot get into the pump.) A downward pointing air nozzle may be needed to further limit the amount of water that can enter the tubing.

The height of your tube could be an issue relative to the pressure generated by standard fish tank air pumps. Most fish tanks I’ve seen are a couple feet high at the most, but if your tube is say 5 or 6 feet, a standard pump may not work – you’ll have to check the vendors for that. (At 6 feet, the pressure needed is about 2.5 psig.)

While acrylic seems to be the material of choice (I assume because of clarity and strength), you might want to check into other materials – I think there is a clear PVC, but even that’s not cheap. (You might try looking through McMaster Carr on line for other materials.)

I suspect the most difficult detail is the piece at the base which must seal the main tube, seal the air supply tube, and be clear to allow lighting from the bottom (at least I am assuming it should be lit from the bottom) and/or seal the light from the water.

A last item – use distilled water to fill it and do your best to keep the water clean. The aeration will favor biological growth. You might need to put in some sort of biocide, but check into that further – it may be easier to just change out the water routinely.


Joe

[Timmyp]

Wow, thanks everyone!

I have found a supplier of Acrylic tubing that will do me 1metre lengths of 10cm diameter for around £10. I can possibly attach two of these together in the Workshops at school, if not then I shall either find another supplier who can do longer pieces, or I shall just use 1m high tubes.

Do you think it would be possible to use one pump to supply air to several bubble tubes?

I shall look into fish tank pumps and also at check valves.

Thanks for your help so far!

Timmy

[koncept]

i would go with a pump per tube (if using fish pumps) depending upon size...