I tried running my CaRx feed pump (using my doser instead of a pump) 9 minutes on, 1 minute off, all day long. And that 1 min off kept causing a build up of c02 in the reactor and the recirculating pump would get noisy, chopping up the c02 bubbles, and all those bubbles were getting caught in the media.Both. I use one for the reactor, and I use the second one 1-speed pump to dose kalkwasser, you can also use aqualifter but they break faster and dump a lot more kalkwasser at the time.
I assume if running only at night u are turning the c02 off as well?