Sorry to hear about your pleco
A good reactor can make a big difference in how efficient your CO2 system is.
Just one point. I hear it's bad to add more than 5ppm nitrate at a time to a tank, as it can be harmful to the fish. I think I read it somewhere on Chuck Gadd's site.
I found that in some of my tanks the plants were initially really "hungry" for nitrates, but this trailed off after a while. Maybe it was the growing fish that produced more nitrates as they got larger.