Here are some more of my "experiences" of the unit in the two plus years that I own one. (XL size in a 300 gal system).
I would recommend the denitrifier, but there are a few details that the user needs to know to get the most benefit of the unit from day one.
I found these things over the course of owning one for 2 years, instead of Midwest having the recommendations included in the manual from day one.
The bottom line is this.
1) start cycling the unit as they recommend in the manual.
2) if your system has hi nitrates (mine was at 80) in a time period of 2 to 3 months your system will be down to 10 or less BUT... the denitrifier will have built up A LOT OF BACTERIA in the reactor because there was a lot of food for the bacteria to munch on.
3) After about 3 months I'd recommend opening up the unit, rinse the sulfur media and put it back but replace the ARM media. Then cycle the unit again per the instruction in the manual. BTW, the unit will cycle a lot faster this time, as the sulfur media is seeded well.
The reason for this sulfur rinse as a first step of maintenance is that as your nitrates go down there is less and less food for the bacteria to feed on so they die off. As they die off, the water starts smelling like rotten eggs and it screws up with the system's water chemistry. (That was my mistake, as I didn't know and left black/dead bacteria in the unti for a long time).
From then on, monitor the unit and once it takes the nitrates down to zero, go thru the above rinsing the sulfur cycle again, and you'll be fine.
The idea is, like everything else in the reef, to create an equilibrium between the nitrates generated by the system, and the amount of nitrate-eating-bacteria in the reactor.
As a word of caution, if you ever see black bacteria in the reactor, open it up and rinse the sulfur.
Other than that, it works great... and it should reduce your nitrate down to zero, provided you do it right.
I wish I had these instructions when I first set up my unit.
Good luck.
