"MarkW" wrote in message ...
I have a top off system for my fishtank that I have a small pump in.
Unfortunately the old float sensor is no longer working so I have to
get a new one. Obviously it's important to be reliable. What is a
good brand to go with? I have seen Ultralife and Reef Fanatic looks
very nice.

They both work on the same principle of a float with a magnet sliding
vertically on a shaft with a reel switch. They should be equally reliable.
The one made by Reef Fanatic have more suction cups, so there is
less risk it will fall off the glass wall...
I have made my switch myself. Got a switch for $6 online he
http://www.aquahub.com/store/ifloatfloatswitch.html and wired it
into a 6ft cheap extension cord using a lamp switch as a fixture.
Simply got 6ft extension cord at Walmart for $1.50, lamp switch for $2
cut one wire around the middle of the lenght, installed lamp switch as
normal, with one exception: I put the two wires coming from the float
switch paralelly with the lamp switch. This way the connection is closed
inside the lamp switch and no wires are exposed to water or touch.
Any scrap plastic/PVC can be cut and bent 90' angle to drill two holes in:
one for a suction cup and the second to install the float switch screw.
And you are done creating a bracket for your switch!

This way for less than $10 I got functional setup I can plug in the water
pump to a christmas light timer and have it configured for once-a-day
top offs replacing evaporated water.
Other idea to use just two wire screws instead of a lamp switch :-)
But I like to have a way to bypass the float switch with a regular
lamp switch for testing/diagnosing :-)

You could check why your switch stopped working - it could be something
simple like cracked wire or float loosing its water-tight. You can also buy
a replacement float switch component of your float switch assembly...
This things are pretty simple - no need to pay big bucks for them :-)