I use a separate timer for the light, CO2, and air pump. I just have not been able to locate a good reliable analog timer. I've been through 2 digital timers, and I won't buy another one. My analog timer for aeration (1 month old), just died. The analog timers do seem to last longer for me. Can anyone recommend a reliable analog timer. I won't even bother to build an "auto-doser", until I can safely locate a viable source that I can depend on. Thanks in-advance for any suggestions.