been using this top off float switch for a couple of years and it has
(Click here for a picture
of the Float Switch parts)
Take a 1 14/" PVC pipe cap and drill four small vent holes around
the edge and a 3/8" hole in the center. (Click here for a picture
of the top cap.) (Click here for a picture
of the top cap - bottom view.)
The float switch is a Madison Miniature Vertical Liquid Level Switch model
Granger has them and their part number is 2A554. This switch will handle
up to a 30 watt load. That is plenty for a powerhead to pump the makeup
water or a solenoid valve on your RO/DI system.
It can be made to be normally open or normally closed by flipping the
little float over. This means that this top-off can be used as a overflow
shut off too.
Cut a short section of 1 1/4" PVC pipe.
Put the pipe cap on one end and a 1 1/4" PVC coupling on the other
(Click here for a picture of the bottom.)
I put a 1 14/" x 1" PVC reducer bushing with a 1" bulkhead
strainer in it so that no snail or fish could go up in the tube and jam
the float switch on.
You can get these bulkhead strainers from www.aquaticeco.com
I am not sure why I made this piece of PVC pipe so long because the
float switch is tiny. It will work long or short.
You will need to make a bracket to hold it that fits your needs. I bent
a piece of acrylic and drilled four holes in it so that I could tie wrap
that float switch assembly to it.
I drilled and tapped two 1/4 20 holes in the back side and installed two
nylon screws so that I could clamp it to the side of my tank.
My tank walls are 6" thick and that is why the bracket is so wide.
You can get nylon screws, nuts, wing nuts and washers from www.aquaticeco.com
by the piece or from www.usplastic.com by the hundred.
You can get a heat tape from www.usplastic.com
for bending up to 24" wide acrylic for $31.49 and 48" wide for
This tape is not fast but it won't burn your acrylic. It works very well.
The float switch comes with 24" long wire leads on it. You will have
to wire this up to an extension cord or an outlet box.
If you are not completely comfortable working with electricity, for
your safety please let some who is take care of this part for you.