Auto top-off float valve ideas needed

[leezer]

I'm building an auto top-off device for my 3 gallon tank. So far, I've built a small circuit driven by a switch and a relay to turn on an air pump. The air pump feeds into a bottle of water, causing the pressure to rise and the water to flow through another tube and into the tank.

The part I'm actually having the most difficulty with is figuring out what to attach to my switch to act as the floatation device. The ideas I've had so far are a piece of cork (possibly coated in wax or silicone to ensure stable bouyancy), styrofoam, or a ping pong ball. Remember, the smaller the better...it is going into a 3 gallon tank.

Any ideas are welcome!

Thanks,
Jon

P.S. I'll add pictures later of the electronics.

 

[runningstix]

You lost me... what are you going to do with the floating device? If you are looking at a way to mount your switch it needs to be mounted in a constant position. If its floating its never going to be actuated.

 

[leezer]

The switch is going to be mounted to a piece of plexiglass which is mounted to the tank. The thing I'm trying to figure out is what to attach to the switch which will float up and down with the water level, thus activating the switch.

 

[leezer]

This picture might help a little.

The red box with a question mark is what I'm looking for suggestions on. It has to be a fairly buoyant object that will be able to force the switch up (and thus turn off the flow of water).

Gotta run to the doctor's. I'll explain more when I get back if the picture hasn't helped.

 

[cbusreefer]

you could use a bobber. they're small, yet boyant...

 

[runningstix]

ahhh. You are diy'ing the float switch. I figured you had the $3 electronic float switch.

 

[leezer]

$3 float switch? Please enlighten me...please, please, please!

 

[runningstix]

well I guess they were $7

http://www.aquahub.com/store/ifloatfloatswitch.html

Im using one of these on my 10g diy ato.

Cut extension chord splice switch in. plug pump into extension chord end. done. (melev style)

http://www.melevsreef.com/plumbing/auto_topoff.html