Originally Posted by Mitchell0605
There are no stupid questions, only stupid answers.
No... actually, there ARE stupid questions.
But this isn't one of them!
No harm will be done using that cartridge on a SW
tank. You aren't going to filter out salt or anything. I've used the diatom filter on my Marineland HOB
a couple times (with no diatomacious earth) on my tank... normally after I've stirred up the sand or added some sand. Depending on what you're trying to filter out, it can muck up pretty quick, so I wouldn't run it for more than 1-2 hours straight or you'll just end up with your pump trying to blow through the clogged filter. But I'm thinking you knew that already!