Lowered my nitrates

[hunggi74]

I've been using Nitra-Guard as well for around two months now. My nitrates were high 50+ppm when I started using it. Now I'm down to 2.5-5ppm. I used the bomb method in my sump. Put it in there two months ago and haven't had to mess with it at all. Very impressed. Does anyone know when the cubes should be changed out? I'd like to be more proactive now rather than wait until I see the nitrate levels climb back up before reacting.