i made a denitrate coil
 

its 3" pvc 2' long. i got 50' of 1/4" tubing as my coil. tried it out in the klitchen and its working with no leaks. what are you guys using for media inside the tube? i was thinking of using the same gravel i got in the tank but that would make it quite heavy. which really isnt a big deal i guess. i just wanted to see what your thoughts were on the matter. ill post a pic asap!

what exactly are you trying to do?

never really heard of a machine to harbor denitrifying bacteria (which converts nitrate to nitrogen gas).. Do you mean nitrifying bacteria, or what?

EDIT- Ah, I see. Here's a link-
http://www.tropicalfishkeeping.com/s...trifier-16131/

so they're usually used in marine tanks? In freshwater, I'd rather just have plants to control nitrates. In marine, there's deep-sand bed and protein skimmers.
Unplanted freshwater? I'd stick to water changes.

If by some crazy fluke I decided to make one, I'd go with something like estes reef sand or pool filter sand.