I see. Yes, it was reading 0 before the CO2 addition. It has been set up for hmmm, about 10 years lol, and onl moved to the bedroom for the last 3 years. Must be the CO2. Questions: will the ammonia then keep rising if I keep it in? Should I move it away from the intake, or take it out altogether until I could get a bubble counter? And regarding fertilizers, are the root tabs that I have sufficient? And is seachem's floursih a good liquid fert?