Quote Originally Posted by sharkboy
It cracked along the lenth of the canister at the corner of one of the grooves that is used to screw on and screw off...The funny thing is that there wasn't any sort of pressure build up since I did a water change earlier in the day...but maybe I did over tighten??? oh well, where can I get a replacement?
Along the groove is where I'd expect them to crack. The groove is there because that is the thinnest part of the cartridge. Most LFS will have them, you can probably find replacements at HDepot, little Ace Hardwares around here in ATX carry them for about $12, you could order them from Buckeye Field supply.

You can also buy gauges really cheap from Buckeye, not to mention the customer service appears to be top notch.