Had a bit of a scare last night. Set up GHL Doser 2.1, primed tubes. Tested manual dosing. No issues save intermittently squeaky pump 1. I had calibrated the pumps a few nights ago. Filled my three dosing containers with 1000ml of ATI Essentials 1, 2, 3. I set it up to start dosing later that evening after I returned from dinner. This was through GHL Connect app for iOS. All three containers in a siphon proof relationship to the sump. Came back to a cloudy aquarium. Ugh. Precisely 200ml of ATI Essentials 1 (alk soln) had dosed while I was gone. However, the indicated volume in the app was still on 999ml. It was set to start dosing hours later (2ml, 10x/d). Pump 1 hangs up occasionally, however, this has decreased through calibrating and priming the system. There should have been no dosing and no dosing was recorded to have occurred while I was out. KH was only at 9.3 from 8.0. The dilute nature of ATI Essentials saved me. I did a 40-50% WC about one hour later. I replaced the dosing solutions with RO water and filled each reservoir to 500ml and set dosing to 5ml 48x/d just to have many successfully doses to regain some confidence. Everything looked fine last night and this AM. Dosing fine now. Recording estimated volume remaining in the containers. I really have no need for a computer and don't own one, but I'm concerned that the Doser 2.1 and/or GHL Connect is buggy right now. I'm going to see if my wife's work lap top will allow me to add GHL Control Center (need a secure WIFI connection anyway). If not I'm going to buy one and a Profilux 4 to have the ability to turn the Doser 2.1 off if I see a rapid pH swing.