I love my ATS! I wanted to share here (this forum) since it has helped me a ton with my questions and I think its super cool that Floyd helps out anyone, whether you bought his, a competitor's, or DIY. Prior to this, I've been using a DIY chaeto reactor. Started out at 4 NO3 and 0.25 PO4 and the chaeto reactor got my NO3 to 0 and my PO4 would hover around 0.16 to 0.20 and would not go down. I dosed KNO3 but PO4 would not budge. My scrubber is from 302aquatics and the model is the AS-2. I bought it used for a great deal. It's a bit oversized for my feeding (2 cubes a day). I started in 01/29 but changed out the lights to this. Photoperiod at 18 hrs/day. A few weeks ago, I stopped dosing dosing KNO3 because I read somewhere that the algae on the screen will shift to phosphate absorbing type once nitrates were very low. This theory didn't work out for me as my phosphates went up. I maybe not have given it enough time...not sure. I started dosing KNO3 again. Today, my PO4 read 0.01! I lowered my photoperiod to 12 hrs and hopefully this will keep my NO3 and PO4 balanced and low but not bottom out. Has anyone ever gotten their nutrients to bottom out using an ATS? All I've read are theories but never heard/read about anyone going too low.