I want to use auto top up without water change. I see you use solenoids etc but my set up would be
3 floats, 1 in the reservoir to stop the pump from running dry and 2 in the sump. About 1cm apart, when water drops and activates the bottom one, it triggers the pump to come on till the water is back to the top float.
Which am scenario would suit me and which arduino pin is for the pump, I can connect it to uln2003a as it's only a small 12v submersible one low milliamp
Thanks