i couldn't tell you what it test's at. you guys can bash me all you want for that, but i've never owned a test kit in over 13 years. i just do my regular water changes as i feel necessary. the water is prestine krisp n clear. the fish are all growing like weeds. i dont think i feed enough to cause crazy spikes and its 400gal of chemistry so it should take a bit to throw it off the chart. all i've done is keep the temp at 82, and add water as it evaps. ill do a wc maybe this weekend since it would be the first.
I have had the same experience with my tanks that are dripped.