Sump water level alarm

[Dozer]

I don't want an auto topoff system- it won't work with my setup and I'm not sure I'd go that route anyway- but I am looking for something that will

1) simply make some kind of noise when the water hits a certain level, to remind us to add water to the sump, or

2) actually shut the electricity off to my return pump if the water hits a certain level.

Either one will work, I guess option 2 is that much safer, option 1 probably simpler. I would like to hear what others might be using for this purpose. Either stuff you can buy or DIY solutions would be greatly appreciated!

Thanks!

[eleyan]

you can do a similar setup to an auto-top off system, but instead of blugging a pump to pump water to the sump, you can plug an alarm. or you can flip the float switch, or reverse the polarity of the relay, so its on when the water level is fine, and it shots off when it goes too low. then you can plug the main return pump to it, and it will turn off when the water level drips.
you can get the float switches off ebay:
http://search.ebay.com/float-switch_Pet-Supplies_W0QQcatrefZC12QQfromZR8QQsacategoryZ1281
I personaly like the mechanical, gravity driven float valves. I have them on both tanks and they work greate with no problem, and no electricity:
https://webspace.utexas.edu/eleyan/tank/equip_page.html