My nitrate has been SLOWLY climbing. Hardly any more than what my tap is at. I just haven't seen nitrites drop to 0 yet. The strips do show 0 in my 20 gal which has been running for about 18 months. I'll pick up a liquid master test kit this weekend and see what it says. As far as bio filter goes, I'm using 1 liter of seachem matrix. Supposedly enough for a 200 gallon tank. I've never used it before, but even if it could only actually support half that I should still be fine. Does anyone have any experience with it? Or the Penn Plax filter for that matter?