Backyard Aquaponics
A place to discuss aquaponics

I found this very inexpensive little float switch and thought it might work well for our applications.

I added the pipe cap and threaded rod as a means of mounting/adjusting.

JPM,
That is a pretty cool switch. It looks like up is off and down is on? Wonder if the wires could be switch for the opposite result? Do you know where I could find more info? Thanks.

The way I mounted the switch it is normally closed and opens when the leve is reached. You can only invert the signal by mounting the switch upside down. I contacted the person I bought this from and they don't have any more although they said they would be coming in. For awhile there were several people selling them on Ebay. Here is another one the I believe could work well for our applications:
http://cgi.ebay.com/Horizontal-Internal ... dZViewItem

One thing to keep in mind about this type of switch is that is only handles about 1/2 amp. This means that you can use the switch to run a relay(either mechanical or solid state) but you certaininly can't run a pump directly off the switch.

The good news is that it does seem reliable and after two months, shows no signs of gumming up.

you can get one very similar to that at Grainger. I believe it is magnetically activated -- ie, there is a reed switch in the tube and the float has a magnet inside that activates the reed switch.
http://www.grainger.com/Grainger/items/2A554 with variations on page 342