When you were using the 1.1 was it running constantly? The 2 1.1 dosing pumps i have both dose 1.5 each. I guess i could run both for 3 ml a minuteI would use the brs with a digital timer. The regular dosers dont hold up well to kalk. I dosed kalk for a few years with one and a 20 brute. I did end up moving to a 50ml minute brs pump because the 1.1ml couldn't keep up. I was at 7200 ml a day when I moved he tank. That method worked very well using one of these timers which allows the on time to be adjusted by the second.