# How to install a background using a garbage bag and a CPAP machine



## ObiQuiet (Oct 9, 2009)

A CPAP machine is a medical device used to treat people with obstructive sleep apnea. It's essentially a self-regulating, low-pressure air pump.

So, faced with the question of how to hold a new background against the glass for many hours while the silicon cured... here's the solution I came up with:









What you're looking at is:
a) an everyday trashbag inside the tank.
b) an airhose duct-taped to the bag

Off-screen is the CPAP air pump which inflates the bag to hold the flexible back ground against the glass.

The CPAP is set to 6 mmhg (1 mmhg = 1/50 psi).  When it detects back-pressure, it automatically stops pumping. This keeps the trash bag gently but firmly inflated.

WARNING: DO NOT try this with a regular air pump or compressor of ANY KIND. You will very quickly BLOW THE TANK APART. Also note that not all CPAPs can limit the pressure. I'm not responsible for damage or injury.

A similar technique would be to line the tank with plastic sheeting and fill it with water until the silicon cures.

Or, you could just flip the tank on its back and use gravity


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## thesawguy (Oct 27, 2012)

This is pretty silly, but I guess you know that. Yet another solution could be stuffing the tank with newspaper, packing materials, towels and so on to hold the background up.


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## rjordan393 (Nov 23, 2012)

Or he could have went to an Arts & Crafts store, purchased a black paper background from the art section and tape it to the outside of the glass. 
My background has been in place for 14 months now. No problems.
I purchased two pieces and splice them together (butt connection) with wide cellophane packaging tape and cut them to size for my 75 gallon. Afterwhich I used regular 1/2 inch tape at both ends. The weight of the paper rests on the bottom rim.


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## thesawguy (Oct 27, 2012)

I just looked closer at your pic and it looks like that background is some sort of reflective sheet or something. If this is the case why is it being installed on the inside?


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## ObiQuiet (Oct 9, 2009)

thesawguy said:


> This is pretty silly, but I guess you know that.


Oh, definitely! We were giggling the whole time.


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## ObiQuiet (Oct 9, 2009)

thesawguy said:


> I just looked closer at your pic and it looks like that background is some sort of reflective sheet or something. If this is the case why is it being installed on the inside?


It's a flexible, 3D backgound from Universal Rocks. Quite nice. Even though my previous background was flat, I had that one on the inside too since the tank has a mirrored back.


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## blue thumb (Mar 30, 2010)

Since the tank was empty why not just lay it on its back and put some heavy books on it.


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## Yo-han (Oct 15, 2010)

blue thumb said:


> Since the tank was empty why not just lay it on its back and put some heavy books on it.


Yes, I always do it this way but with bags of substrate.


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