hi everyone! im looking for a float valve or switch for a DIY auto top off system. i've looked everywhere and havn't found it

. So if anyone has one or knows where i can surely find one please let me know, i want!! i'm looking for a similar one to the one on the bottom of this tread:
http://www.canreef.com/phpBB2/viewtopic.php?t=16398
oh and if anyone knows who sells Spectra Pure stuff in canada please let me know too. Thanks!!!!
-wally